In‐form″al (?), a. [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 visit.
2. Deranged in mind; out of one's senses.
These poor informal women. Shak.