insigne

[in-sig-nee] /ɪnˈsɪg ni/
noun
1.
singular of insignia.
2.
insignia.

insignia

[in-sig-nee-uh] /ɪnˈsɪg ni ə/
noun, formally a plural of, insigne but usually used as a singular with plural, insignia or insignias.
1.
a badge or distinguishing mark of office or honor:
a military insignia.
2.
a distinguishing mark or sign of anything:
an insignia of mourning.
Also, insigne.
Origin
1640-50; < Latin, plural of insigne mark, badge, noun use of neuter 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.
British Dictionary definitions for insigne

insignia

/ɪnˈsɪɡnɪə/
noun (pl) -nias, -nia
1.
a badge or emblem of membership, office, or dignity
2.
a distinguishing sign or mark
Also called (rare) insigne (ɪnˈsɪɡniː)
Word Origin
C17: from Latin: marks, badges, from insignis distinguished by a mark, prominent, from in-² + signum mark
Word Origin and History for insigne

insignia

n.

1640s, from Latin insignia, neuter plural of insigne "badge, mark," from in- "in" (see in- (2)) + signum "mark" (see sign). Singular is insigne.