envelope @ dictionary.com, definition 2.:
something that envelops; a wrapper, integument, or surrounding cover.

usually, in architecture, the envelope is the entire enclosure - what keeps the rain, cold/heat, and bugs out. it's really not that jargon-y...

mapping @ dictionary.com, first two verb usage definitions.:
–verb (used with object)
6.to represent or delineate on or as if on a map.
7.to sketch or plan (often fol. by out): to map out a new career.

to map something onto something else doesn't literally have to mean that you're making a map. just that you're overlaying one kind of information with another in a relational way.

i understand the discomfort with jargon. it can become overbearing - and annoying. but don't mistake good use of good vocabulary for jargon.

some architecture language is necessarily metaphorical. where there isn't a single word or concise description of something, we borrow from an image or action that might be familiar and descriptive. i'd say 'mapping' is an example of that. the point of this kind of metaphor isn't to make the language harder to understand so much as easier to understand - it's an attempt to give you a something to latch onto associatively.

oh, and 'architecture' has two t's.

Thank you for your clear explanation. Thank you so much!