hobby
n. countablen. an activity you do regularly for fun in your free time.
n. an activity pursued regularly in one's leisure time for pleasure.
My hobby is reading.
She took up painting as a hobby to relax after work.
What began as a simple hobby of collecting stamps eventually grew into a serious academic pursuit of philatelic history.
Shortened from hobby-horse, from Middle English hoby, hobyn, hobin (“small horse, pony”), from Old French hobi, haubi, haubby, hobin ("a nag, hobby"; > Modern French aubin, Italian ubino), of Germanic origin: from Old French hober, ober (“to stir, move”), from Old Dutch hobben (“to toss, move up and down”); or from North Germanic origin related to Danish hoppe (“a mare”), Old Swedish hoppa (“a young mare”), North Frisian hoppe (“horse”); both ultimately from Proto-Germanic huppōną (“to hop”), from Proto-Indo-European *kewb- (“to bend; a bend, joint”). More at hop, hobble. The meaning of hobby-horse shifted from "small horse, pony" to "child's toy riding horse" to "favorite pastime or avocation" with the connecting notion being "activity that doesn't go anywhere". Possibly originally from a proper name for a horse, a diminutive of Robert or Robin (compare dobbin).
From Middle English hoby, hobeye, from Old French hobé, hobei, hobet, from Medieval Latin hopētus, diminutive of harpe.