So I can pass along to to our loan officers, what is the technical definition of "dwelling"?

Thank You.

Reg. Z and Reg. C (off the top of my head, there may be others) has a definition of dwelling, and while they're similar, they aren't exact copies of each other. Always a bit dangerous (IMHO) to try to give a sweeping definition of any term that covers the entire compliance world because once you do, you're in danger of the "but you said a dwelling was XYZ". I try to keep all definitions in their own small world (the applicable regulation).

Reg. Z definition: (19) Dwelling means a residential structure that contains one to four units, whether or not that structure is attached to real property. The term includes an individual condominium unit, cooperative unit, mobile home, and trailer, if it is used as a residence.

Reg. C definition: (f) Dwelling means a residential structure, whether or not attached to real property. The term includes but is not limited to a detached home, an individual condominium or cooperative unit, a manufactured home or other factory-built home, or a multifamily residential structure or community.

There's no such thing as a universal definition for any term (you may recall uncertainty about the meaning of the word "is").

For Regulation Z purposes, you're in luck. "Dwelling" is defined by Section 1026.2(a)(19) here: https://www.bankersonline.com/regulations/12-1026-002#2a19

For any other purpose relating to a regulation, look within the reg for definitions. Finding none, it would be a commercially reasonable practice to look definitions in rules with similar coverage.

raitchjay and Richard are right. Let me also add that there are many exceptions and mixed-use properties are difficult. If you want a "technical definition", you have to understand all of the definitions, exemptions and have a full understanding of the regulation. If you want to keep it simple, tell them "it's where someone dwells". Your loan officers aren't probably going to want to have a full understanding, so they need to know to contact you when there are questions or gray areas.