half-life /-ˌlaɪf/
half-life /-ˌlaɪf/ 名詞
半衰期(放射性物質),半存留期(化學物質)
half-life
n : the time required for something to fall to half its initial
value (in particular, the time for half the atoms in a
radioactive substance to disintegrate) [syn: half life]