the.com/strengthen
To add backbone to something that was politely wobbling before.
means To make something stronger, firmer, or more able to resist pressure and last.
from From Old English strengthu (strength), itself rooted in strang, meaning strong or powerful; the -en suffix turns a quality into the act of building it.
Verb factoryThe -en suffix also built sharpen, deepen, harden.
Muscle logicTissue strengthens by repairing micro-damage, not avoiding it.
Grammar twistOne of few verbs ending in two consonant-blends, then -en.