Dictionary.net

A boarding-house is not in common parlance, or in legal meaning, every private house where one or more boarders are kept occasionally only and upon special considerations. But it is a quasi public house, where boarders are generally and habitually kept, and which is held out and known as a place of entertainment of that kind. Cady v. McDowell, 1 Laus. (N. Y.) 486. A boarding-house is not an inn, the distinction being that a boarder is received into a house by a voluntary contract, whereas an innkeeper, in the absence of any reasonable or lawful excuse, is bound to receive a guest when he presents himself. 2 El. & Bl. 144. The distinction between a boarding-house and an inn is that in a boarding-house the guest is under an express contract, at a certain rate for a certain period of time, while in an inn there is no express agreement; the guest, being on his way, is entertained from day to day, according to his business, upon an implied contract. Willard v. Steinhardt, 2 E. D. Smith (N. Y.) 148.

n. A house for boarders.