Noah Webster
Infirm
INFIRM, adjective inferm'. [Latin infirmus; in and firmus.]
1. Not firm or sound; weak; feeble; as an infirm body; an infirm constitution.
2. Weak of mind; irresolute; as infirm of purpose.
3. Not solid or stable.
He who fixes on false principles, treads on infirm ground.
INFIRM, verb transitive inferm'. To weaken. [Not used.]