Half  —n. (pl. Halves) 1 either of two (esp. Equal) parts into which a thing is divided. 2 colloq. Half a pint, esp. Of beer. 3 sport either of two equal periods of play. 4 colloq. Half-price fare or ticket, esp. For a child. 5 colloq. = *half-back. —adj. 1 amounting to half (half the men). 2 forming a half (a half share). —adv. 1 (often in comb.) To the extent of half; partly (half cooked). 2 to some extent (esp. In idiomatic phrases: half dead; am half convinced). 3 (in reckoning time) by the amount of half (an hour etc.) (half past two).  at half cock see *cock1. By half (prec. By too + adj.) Excessively (too clever by half). By halves imperfectly or incompletely (does nothing by halves). Half a mind see *mind. Half the time see *time. Not half 1 slang extremely, violently (he didn't half swear). 2 not nearly (not half long enough). 3 colloq. Not at all (not half bad). [old english]