also half life, 1864, "unsatisfactory way of living," from half + life; the sense in physics, "amount of time it takes half a given amount of radioactivity to decay" is first attested 1907.
half-cent
half-dime
half-eagle
half-hearted
half-hour
half-life
halfling
half-mast
half-measure
half-moon
halfpenny
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