The "operative word" refers to the most important or relevant word in a phrase or sentence. It is the word that carries the main meaning or intention of the statement. Full definition
Mr. Akwasi Kyei explained that operative word used by their flagbearer at the time was «to regularize» and does not mean President Akufo - Addo will allow these miners to cause destruction to vegetation. (ghanapoliticsonline.com)
Love was the big word, sometimes the only operative word, for Fletcher and his like who trivialized Augustine's maxim — «Love God and do as you will» — in the service of moral license. (firstthings.com)
Indeed it is, in much the same way that one applauds obsessive gestures of any and all stripes (or perhaps «swirls» is here the more operative word). (theartsdesk.com)