Lighten up, BD! I am sure that we all appreciate your knowledge and dedication. It just seemed to me that you were being a bit short (or dismissive) with Tim. He did find a word from the same base word, "apoyo," (or "apoyar," depending on whether you think that the noun or the verb is the base) which very easily could have lead to the correct morphology!
Although there is an adjectival form of "apoyo," Spanish does tend to prefer the "sustantivo
" form of expressing what we call "compound nouns" in English.
The adjective form, "apoyante," is used mostly as a noun, meaning "supporter" (ie "supporting one").
Of course, the present participle, "apoyando" in Spanish cannot be used as an adjective.
There are uses of the phrase "arco de apoyo" which do not relate explicitly to architecture.
El apoyo del pie hace un recorrido desde el arco de apoyo al arco de impulso.
.....los intereses del Estado español al ampliar expresamente su arco de apoyo político....
On other pages, "arco de apoyo" is used with the simple meaning of "support arch" as for bridges, and doesn't seem to have the specific meaning of a strainer arch which keeps walls, and stained-glass windows and the like from falling or leaning in!
Are you sure that "arco de apoyo" is the most specific term for a "strainer arch?"
Boy, it's hard to find the exact right terms in another language's jargon.
Good work, BD!
'Experiments are the only means of knowledge at our disposal. The rest is poetry, imagination.' -Max Planck