The Collaborative International Dictionary of English v.0.48:
Firm \Firm\, a. [Compar. Firmer; superl. Firmest.] [OE.
ferme, F. ferme, fr.L. firmus; cf. Skr. dharman support, law,
order, dh? to hold fast, carry. Cf. Farm, Throne.]
1. Fixed; hence, closely compressed; compact; substantial;
hard; solid; -- applied to the matter of bodies; as, firm
flesh; firm muscles, firm wood.
2. Not easily excited or disturbed; unchanging in purpose;
fixed; steady; constant; stable; unshaken; not easily
changed in feelings or will; strong; as, a firm believer;
a firm friend; a firm adherent.
Under spread ensigns, moving nigh, in slow
But firm battalion. --Milton.
By one man's firm obediency fully tried. --Milton.
3. Solid; -- opposed to fluid; as, firm land.
4. Indicating firmness; as, a firm tread; a firm countenance.
Syn: Compact; dense; hard; solid; stanch; robust; strong;
sturdly; fixed; steady; resolute; constant.