a unifying idea that is a recurrent element in a literary or artistic work; "it was the usual `boy gets girl' theme"
(music) melodic subject of a musical composition; "the theme is announced in the first measures"; "the accompanist picked up the idea and elaborated it"
provide with a particular theme or motive; "the restaurant often themes its menus"
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)