In tort law, occupiers' liability, the term is distinguished from invitee; the latter being the person invited whereas the invitor is the person doing the inviting; he who extends the invitation.
In Remedies In Tort, authors L. Klar and A. Linden (Toronto: Carswell, 1987), the authors use the word as follows, in the context of occupiers' liability at common law:
"The duty of an invitor extends to premises which provide access to the invitor’s premises but which are under the ownership, authority, control of a third person. The occupier must take reasonable care to inspect and must warn against any unusual danger to insure that such premises are safe for the invitee to enter and leave the invitor’s premises."
The word is also prevalent in construction law as representing the person who invites tenders or bids on construction projects as in this sample of judicial consideration, from The Queen in Right of Canada v. Ron Engineering and Construction (Eastern) Ltd. 1981 SCR 111:
"The rationale for the tendering process, as can be seen from these documents, is to replace negotiation with competition. This competition entails certain risks for the appellant. The appellant must expend effort and incur expense in preparing its tender.... It must submit its bid security which, although it is returned if the tender is not accepted, is a significant amount of money to raise and have tied up for the period of time .... (T)his procedure is heavily weighted in favour of the invitor. It appears obvious to me that exposing oneself to such risks makes little sense if the respondent is allowed, in effect, to circumscribe this process and accept a non-compliant bid...."