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.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-.The unpronounced termination of many English words.[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.