(noun): An opinion or position agreed upon by a group as a whole by unanimous or nearly unanimous agreement.
----------The traditional bugaboo with today's word is the redundant phrase "consensus of opinion," which seems to mean "an opinion (…) of opinion," a redundant expression if taken literally. However, redundancy is, in fact, the life-blood of language, found commonly in emphatic statements (especially very, very, very emphatic ones), so redundancy is a weak argument for ridding the language of verbal expressions.
----------Plural? ... Simply "consensuses."
----------This is a word we need to work into our conversations more since many things need consensus: "I think we've reached a consensus that we will see 'Lord of the Rings' rather than 'Shrek 2' tonight, right?"
----------However, keep in mind that a consensus may be a convergence of things other than opinions, "The consensus of all the testimony supported the charge that Jarvis did, in fact, switch the signs on the men's and women's restrooms, which led the jury to reach a quick consensus itself."