Origin: 1640–50; < L, pl. of insigne mark, badge, n. use of neut. of insignis distinguished (by a mark); see in-2, sign
Usage note: Insignia, originally the plural of Latin insigne, began to be used as a singular in the 18th century, and the plural insignias appeared shortly thereafter. All uses—insignia as a singular or plural and insignias as a plural—are fully standard. The singular insigne still occurs, but insignia is more common.
in·sig·ni·a (ĭn-sĭg'nē-ə) n.
pl.insignia or in·sig·ni·as
A badge of office, rank, membership, or nationality; an emblem.
A distinguishing sign.
[Latin īnsignia, pl. of īnsigne, badge of office, mark, from neuter of īnsignis, distinguished, marked : in-, in; see in-2 + signum, sign; see sekw-1 in Indo-European roots.]
Usage Note: Insignia in Latin is the plural form of insigne, but it has long been used in English as both a singular and a plural form: The insignia was visible on the wingtip. There are five insignia on various parts of the plane. From the singular use of insignia comes the plural insignias, which is also acceptable. The Latin singular insigne is rare and may strike some readers as pedantic.
[in-sig-nee] 
