1 darling, favourite, idol, apple of (one's) eye, Colloq Brit blue-eyed boy, US fair-haired boy:
You know that you were always Father's pet.
2 tame, trained, domesticated:
Doesn't the landlord take a dim view of your keeping a pet alligator in the bath?
3 favourite, favoured, preferred, cherished, special, particular; indulged, prized, treasured, precious, dearest, adored, darling:
Building the summer-house was Desmond's pet project. Elizabeth's pet pupil is Anne.
4 caress, fondle, stroke, pat; cuddle, nuzzle, nestle, snuggle, Colloq neck, smooch or Australian and New Zealand also smoodge or smooge, Chiefly US and Canadian make out:
Small children need to be petted a lot. Two teenagers were petting in the back seat of the car
5 humour, pamper, favour, baby, coddle, cosset, mollycoddle, cocker, spoil, indulge, dote on:
His mother pets him far too much.
(bad or ill) temper, pique, sulk, (bad) mood, fume, Colloq Brit paddy or paddywhack or paddywack:
He's in a terrible pet because they forgot to cancel the milk when they went on holiday.