Definify.com
Webster 1913 Edition
Informal
In-form′al
,Adj.
[Pref.
in-
not + formal
.] 1.
Not in the regular, usual, or established form; not according to official, conventional, prescribed, or customary forms or rules; irregular; hence, without ceremony;
as, an
. informal
writing, proceeding, or visit2.
Deranged in mind; out of one’s senses.
[Obs.]
These poor
informal
women. Shakespeare
Webster 1828 Edition
Informal
INFORM'AL
,Adj.
1.
Not in the usual manner; not according to custom; as an informal visit.2.
Not with the official forms; as the secretary made to the envoy an informal communication.