FIRM, an adjective originally indicating a dense or close consistency, hence steady, unshaken, unchanging or fixed. This word, in M. Eng. ferme, is derived through the French, from Lat. firmus. The medieval Latin substantive firma meant a fixed payment, either in the way of rent, composition for periodic payments, etc.; and this word, often represented by "firm" in translations of medieval documents, has produced the English "farm" (q.v.). From a late Latin use of firmare, to confirm by signature, firma occurs in many Romanic languages for a signature, and the English "firm" was thus used till the 18th century. From a transferred use came the meaning of a business house. In the Partnership Act 1890, persons who have entered into partnership with one another are called collectively a firm, and the name under which their business is carried on is called the firm-name.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)