agreed-on

the word is a modern english compound adjective formed from the phrasal verb 'agree on'. the core verb 'agree' entered english from old french, tracing back to the latin phrase 'ad grātum', meaning 'to one's liking'. the past participle suffix '-ed' converts the verbal action into a state of being. the preposition 'on' is appended, a common english grammatical construction to specify the topic or object that has been mutually accepted. thus, the literal sense of 'made pleasing upon something' evolved into the modern abstract meaning of a condition or standard that has been jointly decided.

Structure: agree + ed + on agree (from old french 'agreer', ultimately from latin 'ad-' + 'gratus', meaning pleasing, acceptable); ed (english suffix forming the past participle of a verb); on (english preposition, here used to form a compound adjective indicating the subject or basis of the agreement).