Return to the home page.

Expand/collapse menu.

Visit Our Sites

Unabridged Dictionary

Learner's Dictionary

Word Central for Kids

Collegiate Dictionary

Expand/collapse menu.

Premium Services

Unabridged Dictionary

Collegiate Dictionary

Encyclopedia Britannica

Institutional Subscriptions

Expand/collapse menu.

Expand/collapse menu.

Word of the Day

Subscriber Help

Expand/collapse menu.

More Word Games

Daily Crosswords

Expand/collapse menu.

Open Dictionary

Alphabetical Browse

Browse Categories

Submit an Entry

Expand/collapse menu.

Spelling Bee Hive

Hive Headquarters

Spelling Champion

Spelling Reform

Expand/collapse menu.

Word for the Wise

Today's Broadcast

Expand/collapse menu.

Books and CD-Roms

Online Services

Palm and Pocket PC

Expand/collapse menu.

Looking Up a Word

Citing the Dictionary

Audio Pronunciations

Word Games Help

Expand/collapse menu.

Merriam-Webster FAQ

Advertising Info

Copyright Notice

Also Visit:
Unabridged

Visual
ESL:
Learner's
for Kids:
Spell It!
Word Central

ion

Browse the Dictionary:: A; B; C; D; E; F; G; H; I; J; K; L; M; N; O; P; Q; R; S; T; U; V; W; X; Y; Z; #

ion

Main Entry:: ion
Pronunciation:: \ˈī-ən, ˈī-ˌän\
Function:: noun
Etymology:: Greek, neuter of iōn, present participle of ienai to go — more at issue
Date:: circa 1834

1 : an atom or group of atoms that carries a positive or negative electric charge as a result of having lost or gained one or more electrons 2 : a charged subatomic particle (as a free electron)

Learn more about "ion" and related topics at Britannica.com

See a map of "ion" in the Visual Thesaurus

Find Jobs in Your City

Pronunciation Symbols