1 act in advance of in order to prevent.
2 anticipate (the action of another, or an event).
3 anticipate the action of.
4 deal with beforehand.
5 hist. buy up (goods) in order to profit by an enhanced price.
Derivatives:
forestaller n. forestalment n.
Etymology: ME in sense 5: cf. AL forestallare f. OE foresteall an ambush (as FORE-, STALL)
Useful english dictionary. 2012.