e

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

• abbreviation electron
• noun The fifth letter of the modern English alphabet.
• noun Any of the speech sounds represented by the letter e.
• noun The fifth in a series.
• noun Something shaped like the letter E.
• noun A grade that indicates failing status.
• noun The third tone in the scale of C major or the fifth tone in the relative minor scale.
• noun A key or scale in which E is the tonic.
• noun A written or printed note representing this tone.
• noun A string, key, or pipe tuned to the pitch of this tone.
• noun Mathematics The base of the natural system of logarithms, having a numerical value of approximately 2.71828.
• noun The hypothesized textual source of certain narrative portions of the Pentateuch in which God is referred to as Elohim rather than with the Tetragrammaton.

from The Century Dictionary.

• A prefix of Anglo-Saxon origin, one of the forms of the original prefix ge-. It remains unfelt in enough. See i-.
• A prefix of Latin origin, a reduced form of ex-, alternating with ex- before consonants, as in evade, elude, emit, etc. See ex-.
• [capitalized] The sign of residuation (which see).
• [capitalized] In chem., sometimes used as the symbol for erbium: more commonly Er.
• The common symbol for the modulus of elasticity, or the force, in pounds, required to stretch a bar of any material one square inch in cross-section until its length is increased by one hundred per cent.
• In electricity, a symbol for electromotive force.
• An abbreviation of Earl;
• of Eastern;
• of English;
• in experimental psychology, of experimenter.
• The unpronounced termination of many English words.
• The fifth letter and second vowel in our alphabet.
• As a numeral, 250.
• As a symbol: In the calendar, the fifth of the dominical letters.
• In logic, the sign of the universal negative proposition. See A, 2.
• In algebra: [capitalized] The operation of enlargement: thus, Efx = f (x + 1); also, the greatest integer as small as the quantity which follows: thus, . [l. c.] The base of the Napierian system of logarithms; also, the eccentricity of a conic.
• In music: The key-note of the major key of four sharps, having the signature , or of the minor key of one sharp, having the signature ; also, the final of the Phrygian mode in medieval music.
• In the fixed system of solmization, the third tone of the scale, called mi: hence so named by French musicians.
• On the keyboard of the pianoforte, the white key to the right of every group of two black keys.
• The tone given by such a key, or a tone in unison with such a tone.
• The degree of a staff assigned to such a key or tone; with the treble clef, the lower line and upper space .
• A note on such a degree, indicating such a key or tone .
• As an abbreviation: East: as, E. by S., east by south. See S. E., E. S. E., etc.
• In various phrase-abbreviations. See e. g., i. e., E. and O. E., etc.

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

• The fifth letter of the English alphabet.
• (Mus.) E is the third tone of the model diatonic scale. E♭ (E flat) is a tone which is intermediate between D and E.

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

• noun The fifth letter of the basic modern Latin alphabet.
• noun mathematics The base of natural logarithms, a transcendental number with a value of approximately 2.718281828459
• noun close-mid front unrounded vowel
• noun The fifth letter of the English alphabet, called e and written in the Latin script.
• noun The ordinal number fifth, derived from this letter of the English alphabet, called e and written in the Latin script.
• noun The name of the Latin script letter E/e.
• noun mathematics the base of the natural logarithm, 2.718281828459045…

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

• noun the base of the natural system of logarithms; approximately equal to 2.718282...
• noun a fat-soluble vitamin that is essential for normal reproduction; an important antioxidant that neutralizes free radicals in the body
• noun the 5th letter of the Roman alphabet
• noun the cardinal compass point that is at 90 degrees