firm up

Lock it down

Firm up means to make something more definite, solid, or stable.

Plans that are tentative get firmed up when details are confirmed: Let's firm up the meeting time by Friday.

Bodies firm up through exercise.

Prices or markets firm up when they stabilize or strengthen after fluctuation.

The phrase adds a sense of completion or finalization that plain "firm" lacks.

finalize

finalize

Settle decisively

concludeEnd or infer
settleReach final terms
confirmValidate as true

lock in · nail down · cement · close · seal · formalize · ratify · sign off · execute · complete

solidify

harden

Make or become firm

setArrange in position
gelWobbly semi-solid substance
congealSolidify from liquid state

stiffen · thicken · coagulate · crystallize · jell · curdle · clot · solidify · tighten · compact

strengthen

tone

Quality of sound

tightenMake more secure
strengthenMake more robust
sculptShape by carving

define · build · condition · work out · exercise · train · contour · flex · slim down · trim

Categories

hardensolidify, harden, stiffen, set, congeal
strengthenstrengthen, reinforce, fortify, bolster, toughen
finalizationfinalize, conclude, close, clinch, seal

Opposites

definiteness/certainty

firm uphedge

Boundary of planted shrubs

postpone · defer · loosen up · soften · muddy

physical solidity

firm upsoften

Make less firm

loosen · slacken · atrophy · weaken · sag

stability/commitment

firm upback out of

abandon · cancel · dissolve · unravel · fall through

Family

up, firm, firmness, affirm, affirmation, affirmative, firms, firmer, firmed

Familiarity: Top 50,000
Profile: Known to kids · Used worldwide · Timeless · Everyday, not technical · Rated G