half / haf/ • n. (pl. halves / havz/ ) either of two equal or corresponding parts into which something is or can be divided: the northern half of the island two and a half years | divided in half | reduced by half. ∎  either of two equal periods of time into which a sports game or a performance is divided. ∎ Baseball either of the two parts of one inning: the top half of the third. ∎  Golf a score for an individual hole that is the same as one's opponent's. ∎ short for halfback.• pron. & adj. an amount equal to a half: [as pron.] half of the lectures are delivered by him | [as adj.] the last half century. ∎  amounting to a part thought of as roughly a half: [as pron.] half of them are gate-crashers. • adv. to the extent of half: the glass was half full. ∎  [often in comb.] to a certain extent; partly: the chicken is half-cooked.PHRASES: a —— and a half inf. used to indicate that one considers a particular person or thing to be an impressive example of their kind: Aunt Edie was a woman and a half.at half cocksee half cock.go halves share something equally: she promised to go halves with him.half the battlesee battle.half a chance inf. the slightest opportunity: given half a chance, he can make anything work.half an eyesee eye.the half of it inf. the most important part or aspect of something: you don't know the half of it.half past one (two, etc.) thirty minutes after one (two, etc.) o'clock.half the timesee time.not do things by halves do things thoroughly or extravagantly.not half1. not nearly: he is not half such a fool as they thought.2. inf. not at all: the players are not half bad.too —— by half used to emphasize something bad: the idea seems too superstitious by half.