dotard

noun2

1. •
   (no longer used) An old person with impaired intellect; a senile person; one in their dotage.

   • I speake not like a dotard, nor a foole, As vnder priuiledge of age to bragge, What I haue done being yong, or what would doe, Were I not old, […] — 1598
2. •
   (no longer used) One who dotes on another, showing excessive fondness; a doter.