0 to make something more certain or less likely to change:
Could we have a meeting so we can firm up the details of our agreement?
1 to make a part of your body have less fat and more muscle by doing exercise:
Cycling is one of the best ways to firm up your thighs.
My stomach has begun to firm up since I started exercising.
2 to make something more definite or less likely to change:
firm up an agreement/an order/a price The company is attempting to firm up potential orders for four ferries and two cruise ships.
NYA ORD
European
May 10, 2021
DAGENS ORD
Shimmer
firm sth up