Meaning species or kind. From the proverb, “Birds of a feather” —i.e. of the same plumage, and therefore of the same sort.
I am not of that feather to shake off My friend, when he must need me.
Shakespeare: Timon of Athens. i.1.
Feather. A light, volatile person.
A wit's a feather, and a chief a rod; An honest man's the noblest work of God.
Pope: Essay on Man. 247-8.
A broken feather. (See Broken...)
An oiled feather. Kindness of manner and speech. An oiled feather will do more to ease a stubborn lock than great force. (See Power's Tract called The Oiled Feather.)
Birds of a feather flock together. Latin: Similes similibus gaudent. Pares cum paribus facile congregantur. Cicero says, “Deos novimus ornatu et vestitu.”
French: Qui se ressemble, s'assemble. In full feather. Flush of money. In allusion to birds not on the moult. In grand feather. Dressed to the nines.
In high feather. In exuberant spirits, joyous. When birds are moulting they mope about, but as soon as they regain their feathers their spirits revive.
Tickled with a feather. Easily moved to laughter. “Pleased with a feather, tickled with a straw,” is more usual; Rire de la moindre bagatelle.
Also annoyed by trifles, worried by little annoyances.
From day to day some silly things Upset you altogether; There's nought so soon convulsion brings As tickling with a feather. `Gainst minor evils let him pray Who Fortune's favour curries, For one that big misfortunes slay, Ten die of little worries.
Sims: Ballads of Babylon (Little Worries).
Cut a feather. A ship going fast is said to cut a feather, in allusion to the ripple which she throws off from her bows. Metaphorically, “to cut a dash.”
“Jack could never cut a feather.” —Sir W. Scott: The Pirate, xxxiv.
To show a white feather. (See White...)
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894