Stronghold

wiktionary

ref

From Middle English strong-hold, [1] strong-holde, stranghalde (equivalent to strong +‎ hold), from Middle English strong(“having physical strength, sturdy, strong; built to withstand assaults, fortified”) (from Old English strang, strong(“strong”), [2] ultimately from Proto-Indo-European *strengʰ-(“stiff, tight”)) + Middle English hōld(“grasp, grip; control, possession, rule”) (from Old English). [3]

etymonline

ref

stronghold (n.)

early 14c., from strong (adj.) + hold (n.) "fortified place, refuge."