adv. 1 after no long interval of time (shall soon know the result). 2 relatively early (must you go so soon?). 3 (prec. by how) early (with relative rather than distinctive sense) (how soon will it be ready?). 4 readily or willingly (in expressing choice or preference: which would you sooner do?; would as soon stay behind). as (or so) soon as (implying a causal or temporal connection) at the moment that; not later than; as early as (came as soon as I heard about it; disappears as soon as it's time to pay). no sooner ... than at the very moment that (we no sooner arrived than the rain stopped). sooner or later at some future time; eventually. soonish adv.
[ OE sona f. WG ]