Futile, vain, fruitless, bootless, abortive all denote barren of result.
Furnish vs Equip vs Outfit vs Appoint vs Accouter vs Arm
Furnish, equip, outfit, appoint, accouter, arm are comparable when they mean to supply a person or something used by him with the adjuncts necessary or appropriate to his daily living or his occupation.
Furious vs Frantic vs Frenzied vs Wild vs Frenetic vs Delirious vs Rabid
Furious, frantic, frenzied, wild, frenetic, delirious, rabid are comparable when they mean possessed with uncontrollable excitement especially under the stress of a powerful emotion.
Fundamental vs Basic vs Basal vs Underlying vs Radical
Fundamental, basic, basal, underlying, radical are comparable when they mean forming or affecting the groundwork, roots, or lowest part of something.
Function vs Office vs Duty vs Province
Function, office, duty, province are comparable when they mean the act, acts, activities, or operations expected of a person or thing by virtue of his or its nature, structure, status, or position.
Fun vs Jest vs Sport vs Game vs Play
Fun, jest, sport, game, play are comparable when they denote something (as an activity, an utterance, or a form of expression) that provides diversion or amusement or is intended to arouse laughter.
Fulsome vs Oily vs Unctuous vs Oleaginous vs Slick vs Soapy
Fulsome, oily, unctuous, oleaginous, slick, soapy are comparable when they mean too obviously extravagant or ingratiating to be accepted as genuine or sincere.
Full vs Complete vs Plenary vs Replete
Full, complete, plenary, replete are not interchangeable with each other, but the last three are interchangeable with the most comprehensive term, full, in at least one of its senses.
Frustrate vs Thwart vs Foil vs Baffle vs Balk vs Circumvent vs Outwit
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.
Frown vs Scowl vs Glower vs Lower vs Gloom
Frown, scowl, glower, lower, gloom are comparable when they mean to put on a dark or malignant countenance or aspect.
Frighten vs Fright vs Scare vs Alarm vs Terrify vs Terrorize vs Startle vs Affray vs Affright
Frighten, fright, scare, alarm, terrify, terrorize, startle, affray, affright mean to strike or to fill with fear or dread.
Friendship vs Amity vs Comity vs Goodwill
Friendship, amity, comity, goodwill are comparable when they denote the relation (or, in the first three instances, the alliance) existing between persons, communities, states, or peoples that are in accord and in sympathy with each other.