|foretell||some prophets claim to foretell the future.|
|formidable||the steep face of rock we were directed to climb was indeed formidable.|
|foundation||the claim that the sun revolve around the earth has no foundation, because scientific evidence disproves this claim|
|fragile||the Ming dynasty porcelain vase was fragile and needed to be handled carefully|
|frequent|| (adj) he travels so much he's a member of five frequent flyer plans|
(v) my friend loves antique hunting and frequents the local antique shops.