Emily Dickinson Lexicon

FIRM, a. [ferm; L. firmus; Fr. ferme, Sp. firme; It. fermo; W. fyrv. This Welsh word may be from the Latin. The root of the word is probably Celtic; W. fêr, hard, solid; fyr, a solid; feru, to concrete or congeal, to fix, to freeze. This is the root of L. ferrum, iron.]

1. Probably, fixed; hence, applied to the matter of bodies, it signifies closely compressed; compact; hard; solid; as, firm flesh; firm muscles; some species of wood are more firm than others; a cloth of firm texture.
2. Fixed; steady; constant; stable; unshaken; not easily moved; as, a firm believer; a firm friend; a firm adherent or supporter; a firm man, or a man of firm resolution.
3. Solid; not giving way; opposed to fluid; as, firm land.