The story
- Old English · derived fromstīþness“stiffness”
- Middle English · inherited fromstiffenes
- English todaystiffness
From Middle English stiffenes, styffenesse, styfnesse; equivalent to stiff + -ness. Perhaps merging with Middle English stithnesse, stithnysse, from Old English stīþness (“stiffness”).
Etymology from Wiktionary, CC BY-SA 4.0.