Merriam-Webster Collegiate Dictionary - ear

 I. noun  Etymology: Middle English ere, from Old English eare; akin to Old High German ora ~, Latin auris, Greek ous  Date: before 12th century  1.  a. the characteristic vertebrate organ of h~ing and equilibrium consisting in the typical mammal of a sound-collecting outer ~ separated by the tympanic membrane from a sound-transmitting middle ~ that in turn is separated from a sensory inner ~ by membranous fenestrae  b. any of various organs (as of a fish) capable of detecting vibratory motion  2. the external ~ of humans and most mammals  3.  a. the sense or act of h~ing  b. acuity of h~ing  c. sensitivity to musical tone and pitch; also the ability to retain and reproduce music that has been h~d  d. sensitivity to nuances of language especially as revealed in the command of verbal melody and rhythm or in the ability to render a spoken idiom accurately  4. something resembling a mammalian ~ in shape, position, or function: as  a. a projecting part (as a lug or handle)  b. either of a pair of tufts of lengthened feathers on the head of some birds  5. attention, awareness lend an ~  6. a space in the upper corner of the front page of a periodical (as a newspaper) usually containing advertising for the periodical itself or a weather forecast  7. a person who listens ; listener looking for a friendly ~  II. noun  Etymology: Middle English er, from Old English ear; akin to Old High German ahir ~, Old English ecg edge — more at edge  Date: before 12th century the fruiting spike of a cereal (as wheat or Indian corn) including both the seeds and protective structures  III. intransitive verb  Date: 14th century to form ~s in growing the rye should be ~ing up