Usage and Grammar
Q. Does “plus” function like “and” in making two nouns a plural subject? For example, would you say, “This idea plus others like it are gaining traction” or “is gaining traction”?
A. “Plus,” when it’s not acting as a noun (that’s a plus) or as an adjective (a plus sign), can function as either a preposition or a conjunction. As a preposition, it means “in addition to” and takes a singular verb: five plus six equals eleven. As a conjunction, it means “and” and takes a plural verb: a banana plus a loaf of bread were on the table. If the subjects are being considered collectively, use a singular verb; otherwise, opt for the plural. In your example, the ideas alluded to in the subject are gaining traction individually, so “plus” is conjunctive and “are” is the better choice. If you can keep track of all these distinctions, you get an A plus (where “plus” is functioning as an adjective to modify the letter grade).