I often refer to mirepoix ("meer pwah") in my posts. This term from classic French cuisine refers to a small dice of aromatic vegetables for flavoring dishes. When I write "5# mirepoix" on the prep list, our cooks know this is short-hand for "five pounds of onions, carrots, and celery in 3/8" (1 cm) dice in the ratio 2 parts onion to one part each carrot and celery." The 2:1:1 ratio is fairly classic, but many chefs would want a mirepoix in equal parts of each ingredient.
Now were I to write "5# trinity" on my prep list, I would be talking about five pounds of mirepoix of the Cajun holy trinity: onions, peppers, and celery, again with a 2:1:1 ratio.
And if I wanted some other vegetables, I would write something similar to "5# mirepoix of butternut squash, turnips, parsnips, celery root, and rutabaga." The prep cooks would give me equal parts of each unless I specified otherwise.
While I'm on the subject, a similar preparation is the brunoise, 1/8" (3mm) dice of similar vegetables. Brunoise ("bru nwahz") is almost always cut for show (for final garnish that is) so the emphasis is on consistently perfect, identically sized cubes of vegetables.