en

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The letter n.
• noun Printing A space equal to half the width of an em.

from The Century Dictionary.

• noun 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.
• noun 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.
• noun 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.
• noun A common adverbial or prepositional prefix, representing Latin in-, meaning primarily ‘in’ or ‘into.’
• noun 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.
• noun A suffix forming adjectives from nouns of material, as ashen, ashen, earthen, oaken, wooden, golden, sometimes simply -n, as cedarn, eldern, silvern, etc.
• noun The name of the letter N, n. It is rarely written, the symbol N, n, being used instead.
• noun 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.
• noun Abbreviations of encyclopedia.
• noun A termination of various origin, used in the formation of verbs.

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

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

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

• preposition Used in various phrases borrowed from French (see "Derived terms" below).
• noun The name of the Latin script letter N/n.
• noun typography A unit of measurement equal to half of an em (half of the height of the type in use).
• abbreviation English

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

• noun half the width of an em