We have put together a list of words that are similar to FASTNESS.

17 Alternative Words Similar to fastness

1 Speed Noun      Synonym Words Like Speed
2 Fixedness Noun      Synonym Words Like Fixedness
3 Stronghold Noun      Synonym Words Like Stronghold
4 Rate Noun      Synonym Words Like Rate
5 Looseness Noun      Antonym Words Like Looseness
6 Firmness Noun      Synonym Words Like Firmness
7 Security Noun      Synonym Words Like Security
8 Faithfulness Noun      Synonym Words Like Faithfulness
9 Lodging Noun      Hyponym Words Like Lodging
10 Haste Noun      Hyponym Words Like Haste
11 Hurry Noun      Hyponym Words Like Hurry
12 Redoubt Noun      Hyponym
13 Citadel Noun      Hyponym Words Like Citadel
14 Hold Noun      Hyponym Words Like Hold
15 Blockhouse Noun      Hyponym
16 Bastion Noun      Hyponym Words Like Bastion
17 Keep Noun      Hyponym Words Like Keep

1 examples of fastness

1 the enemy retired to their fastnesses in the mountains

10 definitions of fastness

1 The state of being fast and firm; firmness; fixedness; security; faithfulness.
2 A fast place; a stronghold; a fortress or fort; a secure retreat; a castle.
3 Conciseness of style.
4 The state of being fast or swift.
5 the quality of being fixed in place as by some firm attachment
6 a rate (usually rapid) at which something happens
7 a strongly fortified defensive structure
8 The condition or quality of being fast, especially:
9 Firmness; security.
10 Rapidity; swiftness.
We get our data from many different dictionaries across the web:
Wordnik, Wiktionary, Century, American Heritage, Gcide