A thing which is signified or symbolized; a referent.
Late Middle English; earliest use found in Reginald Pecock (c1392–?1459), bishop of Chichester and religious author. From post-classical Latin significatum indication, thing signified, meaning (frequently from 1109 in British sources), use as noun of classical Latin significātum, neuter of past participle of significāre.
Significant, meaningful; important; substantial.
Late 15th century (in an earlier sense).