fastness
noun
fast·ness ˈfas(t)-nəs 
1
: the quality or state of being fast: such as
a
: the quality or state of being fixed
b
: the quality or state of being swift
c
: colorfast quality
d
: resistance (as of an organism) to the action of a usually toxic substance
2
a
: a fortified or secure place
b
: a remote and secluded place
vacationed in their mountain fastness
Synonyms
- celerity
- fleetness
- haste
- hurry
- quickness
- rapidity
- rapidness
- speed
- speediness
- swiftness
- velocity
See all Synonyms & Antonyms 
Example Sentences
the amazing fastness with which the boy took his shower had us wondering if he'd used any water the guerillas retreated to their network of hidden fastnesses deep within the mountains
Recent Examples on the Web Test for color fastness before stitching onto bedding and washing. 
Sonja Carmon, Better Homes & Gardens, 14 Apr. 2021 Given their advance into Labour’s working-class fastness, the Tories’ worst nightmare is not a Labour Party that returns to the old centre as defined by Tony Blair. The Economist, 13 Dec. 2019 The other tragedy occurred far from the public eye, in one of the last remote fastnesses of the world. Ipsita Chakravarty, Quartz India, 10 June 2019 Indeed, Lego can't reach its 2030 goal without solving ABS, a material that affords the company the attributes it so prizes: Durability, color fastness, strength, and clutch power, or how well two joined bricks stay together. Brian Barrett, WIRED, 11 Mar. 2018 These enabled India to detect, and destroy by air, Pakistani troops entrenched in mountain fastnesses. Tunku Varadarajan, WSJ, 5 July 2017 India kept the mostly Hindu rest of Jammu, the Vale itself and the desert-like fastness of Ladakh. The Economist, 20 July 2017 See More
Sonja Carmon, Better Homes & Gardens, 14 Apr. 2021 Given their advance into Labour’s working-class fastness, the Tories’ worst nightmare is not a Labour Party that returns to the old centre as defined by Tony Blair. The Economist, 13 Dec. 2019 The other tragedy occurred far from the public eye, in one of the last remote fastnesses of the world. Ipsita Chakravarty, Quartz India, 10 June 2019 Indeed, Lego can't reach its 2030 goal without solving ABS, a material that affords the company the attributes it so prizes: Durability, color fastness, strength, and clutch power, or how well two joined bricks stay together. Brian Barrett, WIRED, 11 Mar. 2018 These enabled India to detect, and destroy by air, Pakistani troops entrenched in mountain fastnesses. Tunku Varadarajan, WSJ, 5 July 2017 India kept the mostly Hindu rest of Jammu, the Vale itself and the desert-like fastness of Ladakh. The Economist, 20 July 2017 See More Word History
First Known Use
before the 12th century, in the meaning defined at sense 1
Medical Definition
fastness
noun
fast·ness ˈfas(t)-nəs
: resistance (as of an organism) to the action of a usually toxic substance
streptomycin fastness developed by a strain of tubercule bacillus
fastness
noun
1
as in speed
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 & Similar Words
Relevance
- speed
- velocity
- rapidity
- rate
- swiftness
- quickness
- celerity
- hurry
- speediness
- rapidness
- pace
- fleetness
- acceleration
- haste
- tempo
- gait
- promptness
- expedition
- precipitation
- alacrity
- promptitude
- expeditiousness
- clip
- hastiness
- rush
- dispatch
- hustle
- precipitousness
- drive
- warp speed
Antonyms & Near Antonyms
- slowness
- sluggishness
- lethargy
- torpidity
- reluctance
- languor
- languidness
- deliberateness
- leisureliness
- deliberation
- torpor
- dilatoriness
- lateness
- procrastination
- pokiness
2
as in stronghold
a structure or place from which one can resist attack the guerillas retreated to their network of hidden fastnesses deep within the mountains Synonyms & Similar Words
- stronghold
- fortress
- bastion
- citadel
- fortification
- castle
- fort
- rampart
- redoubt
- parapet
- bunker
- embattlement
- bulwark
- battlement
- hold
- breastwork
- earthwork
- blockhouse
- alcazar
- casbah
- dugout
- garrison house
- kasbah
3
as in loyalty
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 & Similar Words
- loyalty
- allegiance
- fidelity
- dedication
- commitment
- devotion
- steadfastness
- faithfulness
- constancy
- adhesion
- fealty
- attachment
- devotedness
- reliability
- dependability
- piety
- faith
- affection
- firmness
- trustworthiness
- troth
- determination
- fondness
- resolution
- trustability
- trustiness
Antonyms & Near Antonyms
- inconstancy
- treachery
- perfidy
- disloyalty
- falsity
- faithlessness
- unfaithfulness
- falseness
- infidelity
- separation
- alienation
- perfidiousness
- disaffection
- estrangement