Es

from The Century Dictionary.

• noun In music, E♭.
• noun See ess.
• noun A prefix of Latin origin, being a French or other Romance modification of Latin ex-.
• noun An apparent prefix, of Romance origin, being radical initial s before another consonant, preceded by a slight euphonic vowel, as in escalade, esquire, especial, estate, estray, of ultimate Latin origin, and escarp, eschew, etc., of Teutonic origin, some of which have also forms (original or aphetic) without the e-, as scutcheon, squire, special, state, stray, etc., while some with original (Old French or Middle English) es- have only s-in modern English, as scrivener, spiritual, strain, etc.
• noun The early form of the possessive or genitive case singular, now regularly written 's, but still pronounced as -es (-ez) after a sibilant, namely, s, z, sh, ch (= tsh), j, written -dge, -ge (= dzh), x (= ks), as in lass's, pace's, horse's, rose's, bush's, church's, hedge's, fox's, etc. (formerly written lasses, paces, horses, roses, bushes, churches, hedges, foxes, etc.), words forced to conform in spelling to other words, like boy's, man's, etc. (formerly written boys, mans, etc.), where the e is actually suppressed in pronunciation; in Middle English and earlier the suffix was regularly -es, which still remains in possessives like horses (Anglo-Saxon and Middle English horses), guides (Middle English gides), now written with the apostrophe, like other words, horse's, guide's. See -s.
• noun The earlier form of the now more common plural suffix -s, retained after a sibilant (like the phonetically similar possessive suffix: see -es), as in lasses, paces, horses, roses, bushes, churches, hedges, foxes, etc.
• noun The earlier form of -s, the suffix of the third person singular of the present indicative of verbs, retained after a vowel, as in huzzaes, goes, does, etc. When the infinitive ends in silent e, the personal suffix is regarded, orthographically, as simply -s, but it is historically -es, the infinitive -e being dropped before inflectional suffixes, as in rues, endues, etc., defies, supplies, accompanies, etc., infinitive rue, endue, defy, accompany, etc., the termination -y being formerly -ie.
• noun The nominative singular termination of some Latin nouns and adjectives of the third declension. Examples of such nouns, used in New Latin or English, are tabes, pubes.
• noun The nominative plural termination of Latin masculine and feminine nouns and adjectives of the third declension. Examples of such nouns, used in New Latin or English, are Aves, Pisces, fasces.
• An abbreviation of east-southeast.

from the GNU version of the Collaborative International Dictionary of English.

• noun the chemical symbol for einsteinium, a transuranic element with atomic number 99. The atomic weight of the longest-lived isotope, with a half-life of 276 days, is 254. The first isotope discovered, having atomic weight 253 and a half-life of 20 days, was recognized in 1952 in the debris from a hydrogen bomb test. As much as 3 micrograms of einsteinium were produced by a complex process involving long irradiation of plutonium isotopes in nuclear reactors. Its chemical properties are those of a trivalent actinide element.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun chemistry Symbol for einsteinium.
• noun metrology Symbol for the exasecond, an SI unit of time equal to 1018 seconds.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a radioactive transuranic element produced by bombarding plutonium with neutrons