FIRMER

Steadfast, secure, solid (in position)

"It's good to have a firm grip when shaking hands."

Fixed (in opinion)

"He was firm that selling his company would a good choice and didn't let anyone talk him out of it."

Durable, rigid (material state)

"firm flesh; firm muscles, firm wood; firm land (i.e. not soft and marshy)"

A physical exercise or cosmetic product intended to firm part of the body.

"face firmers"

A thin chisel with a tang to enter the handle instead of a socket for receiving it.