to worry a lot about things that may not be very important:
I wish you'd stop fussing - I'll be perfectly all right.
to pay too much attention to small unimportant details
Paul was fussing with his clothes, trying to get his tie straight.
3 American English
to behave in an unhappy or angry way:
The baby woke up and started to fuss.
fuss over somebody/somethingphrasal verb
His aunts fussed over him all the time.