n.
Pronunciation: ' fo ̇ i(- ə )l
Function: transitive verb
Etymology: Middle English, alteration of fullen to full cloth, from Anglo-French foller ― more at FULL
Date: 14th century
1 obsolete : TRAMPLE
2 a : to prevent from attaining an end : DEFEAT <always able to foil her enemies> b : to bring to naught : THWART < foil ed the plot>
synonyms see FRUSTRATE