This list includes 48 Big words that start with X, from “xanthoma” to “xylotomy”. These entries are mainly polysyllabic, formal, and often rare, useful for writing, teaching, and vocabulary study.
Big words that start with X are advanced, polysyllabic English words beginning with X, often drawn from Greek or Latin. For example, “xanthoma” comes from Greek xanthos, meaning “yellow”.
Below you’ll find the table with Word, Etymology, and Definition.
Word: The headword itself, alphabetized so you can quickly locate entries for writing, study, or reference.
Etymology: Brief origins and root morphemes show where the word comes from and help you understand meaning.
Definition: One-sentence, clear meanings that you can use directly in writing or to check precise usage.
Big words that start with X
| Word | Part of speech | Syllables | Etymology |
|---|---|---|---|
| xenophobia | noun | 5 | Greek xénos “stranger” + phóbos “fear”, 19th c. |
| xenophobic | adj. | 4 | Greek xénos + phóbos, 19th c. |
| xenophile | noun | 3 | Greek xénos “stranger” + philía “love”, 19th c. |
| xenophilia | noun | 5 | Greek xénos + philía “love”, 19th c. |
| xenogenesis | noun | 4 | Greek xénos “stranger” + genesis “origin”, 19th c. |
| xenograft | noun | 3 | Greek xénos “foreign” + graft, medical 19th c. |
| xenogeneic | adj. | 4 | Greek xénos + genetikos “genetic”, 19th–20th c. |
| xenobiotic | noun | 4 | Greek xénos “foreign” + biōtikos “life”, 20th c. |
| xenobiology | noun | 5 | Greek xénos + biology, 20th c. |
| xenoglossy | noun | 4 | Greek xénos “foreign” + glōssa “tongue”, 19th c. |
| xenoglossia | noun | 4 | Greek xénos + glōssa “tongue”, 19th c. |
| xenogamy | noun | 4 | Greek xénos “other” + gamos “marriage”, botany |
| xenial | adj. | 3 | Greek xénos “stranger/guest”, classical/19th c. |
| xenodochial | adj. | 5 | Greek xénos + dokhē “reception”, medieval/18th–19th c. |
| xenodochium | noun | 5 | Medieval Latin from Greek xenodocheion “guesthouse”, medieval era. |
| xenolithic | adj. | 4 | Greek xénos “foreign” + lithos “stone”, geology. |
| xenolith | noun | 3 | Greek xénos + lithos “stone”, geology. |
| xenomorph | noun | 3 | Greek xénos “foreign” + morphē “form”, modern usage. |
| xenomorphic | adj. | 4 | Greek xénos + morphē “form”, 19th–20th c. |
| xenotropic | adj. | 4 | Greek xénos “foreign” + trope “turn”, virology. |
| xenotransplantation | noun | 6 | Greek xénos + Latin trans- + transplantatio, 20th c. |
| xenotransplant | noun | 4 | Greek xénos + transplant, 20th c. |
| xoanon | noun | 3 | Greek xōanon “wooden cult image”, classical Greek. |
| xerography | noun | 4 | Greek xēros “dry” + graphē “writing”, 20th c. |
| xerophilous | adj. | 4 | Greek xēros “dry” + phil- “loving”, ecology. |
| xerophile | noun | 4 | Greek xēros “dry” + phil- “loving”, biology. |
| xerophagy | noun | 4 | Greek xēros “dry” + phagos “eating”, religious/medical. |
| xerophthalmia | noun | 5 | Greek xēros “dry” + ophthalmos “eye”, medical. |
| xerothermic | adj. | 4 | Greek xēros “dry” + thermē “heat”, ecology. |
| xanthophyll | noun | 3 | Greek xanthos “yellow” + phyllon “leaf”, 19th c. |
| xanthoma | noun | 3 | Greek xanthos “yellow” + -oma “tumor”, medical. |
| xanthomatosis | noun | 5 | Greek xanthos + -osis “condition”, medical. |
| xylography | noun | 4 | Greek xylon “wood” + graphē “writing”, historical printing. |
| xylograph | noun | 3 | Greek xylon + graphē, printing. |
| xylophagous | adj. | 4 | Greek xylon “wood” + phagein “to eat”, biology. |
| xylophone | noun | 3 | Greek xylon “wood” + phōnē “sound”, 19th c. |
| xylotomy | noun | 4 | Greek xylon + tomē “cutting”, microscopy/anatomy. |
| xylotomous | adj. | 4 | Greek xylon + tomē “cutting”, entomology. |
| xylocarp | noun | 3 | Greek xylon “wood” + karpos “fruit”, botany. |
| xylophilous | adj. | 4 | Greek xylon “wood” + phil- “loving”, ecology. |
| xenocryst | noun | 3 | Greek xénos “foreign” + krystallos “crystal”, geology. |
| xenocrystic | adj. | 4 | Greek xénos + krystallos, geology. |
| xenodiagnosis | noun | 5 | Greek xénos “foreign” + diagnosis, medical parasitology. |
| xenodiagnostic | adj. | 5 | Greek xénos + diagnosis, medical. |
| xenoblastic | adj. | 4 | Greek xénos “foreign” + blastos “germ/sprout”, petrology. |
| xenoglossic | adj. | 4 | Greek xénos + glōssa “tongue”, 19th c. |
| xenomelia | noun | 4 | Greek xénos “foreign” + mélos “limb”, neurology/psychiatry. |
| xenomania | noun | 4 | Greek xénos “foreign” + mania “obsession”, 19th c. |
Descriptions
xenophobia
Intense dislike or fear of foreigners or strangers, often used in social and political contexts.
xenophobic
Describing attitudes or behaviors that are hostile toward foreigners or unfamiliar groups.
xenophile
A person attracted to foreign cultures, peoples, or customs; opposite of xenophobe.
xenophilia
An appreciation for or attraction to foreign peoples, cultures, or ideas.
xenogenesis
Hypothesized production of offspring markedly different from their parents; historically used in biology and literature.
xenograft
A graft or transplant of tissue between individuals of different species.
xenogeneic
Derived from or involving tissues of different species; used in transplantation biology.
xenobiotic
A chemical compound foreign to a biological system, such as pollutants or some drugs.
xenobiology
Study or speculation about life forms with fundamentally different biochemistries from Earth’s life.
xenoglossy
Alleged phenomenon of speaking or understanding a language one has not learned.
xenoglossia
Alternate term for xenoglossy; claimed sudden ability to speak an unknown language.
xenogamy
Cross-fertilization between genetically distinct individuals or populations in plants.
xenial
Pertaining to hospitality between host and guest; hospitable, especially in older usage.
xenodochial
Hospitable or relating to receiving strangers; a rare, high-register word for hospitality.
xenodochium
A medieval guesthouse or hospital for strangers; historical ecclesiastical term.
xenolithic
Describing rock fragments that are foreign to the igneous rock in which they occur.
xenolith
A piece of rock trapped in another rock, notably in igneous bodies, that differs in origin.
xenomorph
An organism or form that appears markedly alien or structurally foreign; common in science fiction.
xenomorphic
Having a foreign or irregular form; used in biology and descriptive contexts.
xenotropic
Describing viruses that preferentially infect species other than the original host.
xenotransplantation
The transplantation of organs, tissues, or cells between different species, especially to humans.
xenotransplant
A transplant procedure or graft taken from an animal to a human (or between species).
xoanon
An ancient carved wooden cult statue, especially those worshipped in classical Greek sanctuaries.
xerography
A dry copying and printing process used in photocopy machines and laser printing.
xerophilous
Adapted to, thriving in, or preferring very dry environments.
xerophile
An organism adapted to and flourishing in extremely dry conditions.
xerophagy
A practice or diet of consuming only dry foods, historically used in fasting contexts.
xerophthalmia
A medical condition of extreme eye dryness that can impair vision, often from vitamin A deficiency.
xerothermic
Characterized by hot, dry environmental conditions; used in climatology and ecology.
xanthophyll
Yellow plant pigment important in photosynthesis and leaf coloration.
xanthoma
A yellowish deposit of cholesterol under the skin, often indicating lipid metabolism disorders.
xanthomatosis
A disorder characterized by the presence of multiple xanthomas or fatty skin deposits.
xylography
The art or process of engraving on wood and printing from woodblocks.
xylograph
A wood engraving or the print made from such an engraving.
xylophagous
Feeding on wood; used to describe insects and organisms that consume woody material.
xylophone
A musical instrument with tuned wooden bars struck to produce pitched sounds.
xylotomy
The preparation of thin wood sections for microscopic or structural study.
xylotomous
Capable of boring into or cutting wood; describing certain insect behaviors.
xylocarp
A fruit with a woody outer shell, such as a coconut; botanical term.
xylophilous
Attracted to or living on wood; describes organisms that favor woody substrates.
xenocryst
A crystal in an igneous rock that is foreign to the rock’s main mineral assemblage.
xenocrystic
Pertaining to or containing xenocrysts; describes rocks with foreign crystals.
xenodiagnosis
A diagnostic method using an uninfected vector to detect pathogens in a host.
xenodiagnostic
Relating to or used in xenodiagnosis, a technique in parasitology.
xenoblastic
Describing mineral grains that formed earlier and are foreign to the surrounding matrix.
xenoglossic
Relating to xenoglossy; describing claimed speaking of languages not learned.
xenomelia
A rare condition in which a person feels a limb is foreign or does not belong.
xenomania
An excessive enthusiasm for foreign cultures, fashions, or influences; rare, high-register term.