Definition of "insignia"

The little green men were clearly professional soldiers by their bearing, carried Russian weapons, and wore Russian combat fatigues, but they had no identifying insignia. Vladimir Putin originally denied they were Russian soldiers; that April, he confirmed they were.

2019 March 18, Steven Pifer, Five years after Crimea’s illegal annexation, the issue is no closer to resolution‎, The Center for International Security and Cooperation

The former Protector tendered him the oaths, and presented him with the insignia of office, performing the ceremonies of installation.

1826, [Mary Shelley], chapter VI, in The Last Man. […], volume I, London: Henry Colburn, […]

But if autumn wear the insignia of nature's royalty, its purple and gold, in only the shaded lane or the green field with its one or two old trees, what is its more than eastern pomp in a wooded empire like the New Forest!

1834, L[etitia] E[lizabeth] L[andon], chapter XI, in Francesca Carrara. […], volume III, London: Richard Bentley, […], (successor to Henry Colburn), page 80

Rule 23: “The stress of love makes it hard to eat and sleep.” To these empirical laws we can add the various other insignia of love.

2006, P. Goodrich, The Laws of Love: A Brief Historical and Practical Manual, page 49