Frustrate, thwart, foil, baffle, balk, circumvent, outwit mean either to defeat a person attempting or hoping to achieve an end or satisfy a desire or, in some cases, to defeat another’s desire.
To frustrate is to make vain or ineffectual all efforts, however feeble or however vigorous, to fulfill one’s intention or desire.
To thwart is to frustrate especially by crossing or running counter to someone or something making headway.
Foil commonly implies a blocking or turning aside that makes further effort difficult or destroys one’s inclination to proceed further.
To baffle is to frustrate especially by confusing or puzzling; to balk, by interposing obstacles or hindrances.
Circumvent implies frustration by stratagem; outwit, by craft or cunning.