en

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. The letter n.
2. n. Printing A space equal to half the width of an em.

Century Dictionary and Cyclopedia

1. n. The name of the letter N, n. It is rarely written, the symbol N, n, being used instead.
2. n. In printing, a space half as wide as an em, sometimes used as a standard in reckoning the amount of a compositor's work. See em, 2.
3. n. A common adverbial or prepositional prefix, representing Latin in-, meaning primarily ‘in’ or ‘into.’ Appearing first in Middle English words derived through Old French from Latin, en- (before labials em-) has come to be freely used as a prefix of words of native as well as of Romance or Latin origin, being equivalent to in- of pure English origin and to in- of direct Latin origin, and hence often restored to the pure Latin form. Hence forms in en- (em-) and in- (im-) are frequently found (even in Middle English) coexisting, as enclose, inclose, enquire, inquire, enwrap, inwrap, enfold, infold, with, however, a tendency in one or other of the forms to disappear, or to become partly differentiated in use. Before labials en- becomes em-, as in embellish, embrace, but may remain unchanged before m, as in enmew or emmew. As a verbal prefix, en-, when joined to a noun, or a verb from a noun, may retain its original meaning of ‘in’ (‘put in’), as in encage (put in a cage), enfold, enfetter, encapsule, etc.; or when prefixed to an adjective or a noun, it may denote a change from one state into another (‘make …’), as in enable (make able), enrich, enslave, enfranchise, enlarge, and hence has often the effect simply of a verb-forming prefix. In some cases, prefixed to a verb, it has no additional force, as in enkindle, encaptivate.
4. n. An adverbial or prepositional prefix of Greek origin, meaning primarily ‘in’: chiefly in scientific or technical words of modern formation, as in encephalon, enanthema, etc.
5. n. A termination of various origin, used in the formation of verbs. The infinitive suffix, now obsolete, as in Middle English singen, escapen, pullen, etc., modern English sing, escape, pull, etc. In late Middle English the -n fell away (singe, escape, pulle, etc.), but the -e continued to be pronounced, at least optionally, until near the end of the Middle English period; in modern English the -e, though always silent, is retained in spelling after a single consonant following a long vowel (as in escape) and in some other positions.
6. n. A suffix forming adjectives from nouns of material, as ashen, ashen, earthen, oaken, wooden, golden, sometimes simply -n, as cedarn, eldern, silvern, etc. Many such words are obsolete, dialectic, or archaic, as elmen, treen, clayen, hairen, etc.; many are also, some chiefly or exclusively, nouns, as aspen, linden, linen, woolen.
7. n. A feminine suffix, of which only a few relics exist in native English words, as, for example, vixen, from Anglo-Saxon fyxen (= German füchsin), a female fox: in some instances regarded as having a diminutive force, as in maiden, from Anglo-Saxon mægden, etc. See vixen, maiden, and compare elfin.
8. n. The plural suffix of a few nouns, as oxen, brethren, children, and (archaic and poetical) eyne or een (= eyen), kine (= kyen), shoon, dial. hosen, housen, peasen, etc. In these the termination is of Middle English origin, except in oxen (from Anglo-Saxon oxan), eyne, een (from Anglo-Saxon eágan), hosen (from Anglo-Saxon hosan), peasen (from Anglo-Saxon pisan).
9. n. A suffix of various other origins besides those mentioned above: often ultimately identical with -an (Latin -anus), as in citizen, denizen, dozen, etc., but having also, as in often, midden, etc., other sources ascertainable upon reference to the word concerned.
10. n. Abbreviations of encyclopedia.

Wiktionary

1. abbr. English
2. n. The name of the Latin script letter N/n.
3. n. typography A unit of measurement equal to half of an em (half of the height of the type in use).
4. prep. Used in various phrases borrowed from French (see "Derived terms" below).

GNU Webster's 1913

1. n. (Print.) Half an em, that is, half of the unit of space in measuring printed matter. See em.

WordNet 3.0

1. n. half the width of an em