Ban.
banned
Ban
allowedpermittedapproved of
forbid
Apt.
Nil.
"wee"
Synonyms for prohibit: banned, ban, disallow, forbid, hinder, prevent.
foe
A three letter synonym for a verse is ode.
A three letter synonym for the exclamation 'gosh' is gee.
A three letter synonym for 'present' is now.