(s)quick, speedyaccomplished rapidly and without delay“was quick to make friends”, “his quick reaction prevented an accident”, “hoped for a speedy resolution of the problem”, “a speedy recovery”, “he has a right to a speedy trial”
(s)agile, nimble, quick, sprymoving quickly and lightly“sleek and agile as a gymnast”, “as nimble as a deer”, “nimble fingers”, “quick of foot”, “the old dog was so spry it was halfway up the stairs before we could stop it”
(s)immediate, prompt, quick, straightawayperformed with little or no delay“an immediate reply to my letter”, “a prompt reply”, “was quick to respond”, “a straightaway denial”