Almost every word is a synonym for something - or an antonym.
allow, admit
It is neither.
let as a noun - encumbrancelet as a verb - allow, enable, rent
authorize, allow, commission, qualify, permit, sanction, entitle, delegate
agree to, allow, pass, recommend, permit, sanction, endorse, authorize
A homophone for "allow" that is also a synonym is "aloud."
Authorize
allow
allow, admit
allow access
Endorse is a synonym for allow. It begins with the letter E.
It is neither.
allow (v)license (n, v)
let as a noun - encumbrancelet as a verb - allow, enable, rent
suffragists (Suffer used to be a synonym of allow.)
authorize, allow, commission, qualify, permit, sanction, entitle, delegate
agree to, allow, pass, recommend, permit, sanction, endorse, authorize