fain

Etymology 1

From Middle English fain, from Old English fægen, from Proto-Germanic *faganaz (“glad”), from Proto-Indo-European *peḱ- (“to make pretty, please oneself”); akin to Old Norse feginn (“glad, joyful”), Gothic 𐍆𐌰𐌲𐌹𐌽𐍉𐌽 (faginōn, “to rejoice”), Old Norse fagna (“to rejoice”).

adj

1. (archaic) Well-pleased, glad.
2. (archaic) Satisfied, contented.
   O love, of my death my life is fain, 1883, Dante Gabriel Rossetti, A Death-Parting, line 11, Poems
3. (archaic) Eager, willing or inclined to.
4. (archaic) Obliged or compelled to.

Etymology 2

From Middle English fain, fayn, feyn, from the adjective (see above).

adv

1. (archaic) With joy; gladly.
   Yet dearly I love you, and would be loved fain, 1633, John Donne, Holly Sonnets, section XIV
   […] and fain would I inhale it in all its pristine fulness and vigour. 1891, George Du Maurier, Peter Ibbetson
2. (archaic) By will or choice.

Etymology 3

From Middle English fainen, from Old English fæġnian, from Proto-West Germanic *faginōn, from Proto-Germanic *faginōną.

verb

1. (archaic) To be delighted or glad; to rejoice.
2. (archaic) To gladden.
3. (Germanic paganism) to worship, to celebrate, to offer an oblation which is not sacrificial blót.