fastness

1 a high rate of movement or performance the amazing fastness with which the boy took his shower had us wondering if he'd used any water Synonyms celerity, speed, fleetness, haste, hurry, quickness, rapidity, rapidness, speediness, swiftness, velocityRelated Words clip, gait, pace, rate, tempo; drive, hustle; acceleration, hastiness, precipitation, precipitousness, rush; alacrity, dispatch, expedition, expeditiousness, promptitude, promptness; warp speedNear Antonyms languidness, languor, leisureliness, lethargy, torpidity, torpor; reluctance; deliberateness, deliberation; dilatoriness, lateness, pokiness, procrastinationAntonyms slowness, sluggishness

2 a structure or place from which one can resist attack the guerillas retreated to their network of hidden fastnesses deep within the mountains Synonyms bastion, castle, citadel, fort, fortification, fortress, hold, redoubt, strongholdRelated Words battlement, breastwork, bulwark, earthwork, embattlement, parapet, rampart; bunker, dugout; blockhouse, garrison house; alcazar, casbah (also kasbah)

3 adherence to something to which one is bound by a pledge or duty his uncompromising fastness to the cause of freedom was beyond question Synonyms adhesion, allegiance, attachment, commitment, constancy, dedication, devotedness, devotion, faith, faithfulness, fidelity, fealty, loyalty, piety, steadfastness, trothRelated Words affection, fondness; determination, firmness, resolution; dependability, reliability, trustability, trustiness, trustworthinessNear Antonyms alienation, disaffection, estrangement, separationAntonyms disloyalty, faithlessness, falseness, falsity, inconstancy, infidelity, perfidiousness, perfidy, treachery, unfaithfulness