an activity or interest pursued for pleasure or relaxation and not as a main occupation

Her hobbies include stamp-collecting and woodcarving.

a child's hobbyhorse.

Archaic . a small horse. ?

ride a hobby, to concern oneself excessively with a favorite notion or activity. Also

ride a hobbyhorse.

noun

profession , vocation , work

noun

amusement , art , avocation , bag * , craft , craze , distraction , diversion , divertissement , fad * , fancy , favorite occupation , fun , game , interest , kick * , labor of love * , leisure activity , leisure pursuit , obsession , occupation , pet topic , play , quest , relaxation , schtick , shot , sideline , specialty , sport , thing * , vagary , weakness , whim , whimsy , activity , enjoyment , fad , pastime