A thin, often triangular flag or streamer, especially as hung from the end of a lance or spear.
1863, Christina Rossetti, “A Royal Princess” in Isa Craig (ed.), An Offering to Lancashire, London: Emily Faithfull, p. 3,
Vassal counts and princes follow where his pennon goes,
(nautical) A long pointed streamer or flag on a vessel.
1631, Michael Drayton, The Battaile of Agincourt, London: William Lee, p. 21,
… a ship most neatly that was lim’d,
In all her sailes with Flags and Pennons trim’d.
1780, Hannah Cowley, The Maid of Arragon, London: L. Davis et al.,
Fair Commerce wav’d her pennons in our ports;
(literary, obsolete) A wing (appendage of an animal's body enabling it to fly); any of the outermost primary feathers on a wing.
1630, Henry Lord, A Display of Two Forraigne Sects in the East Indies, London: Francis Constable, “The Religion of the Persees,” Chapter 4, p. 16,
[…] sodainly there descended before him, as his face was bent towards the earth, an Angell, whose wings had glorious Pennons, and whose face glistered as the beames of the Sunne,