Today's NYT Connections game #521 had 4 groups: yellow, green, blue and purpleThe yellow group items were canary, lemon, minion, mustardThe green group items were addition, annex, extension, wingThe blue group items were calculus, cavity, plaque, tartarThe purple group items were colonel, pharaoh, Wednesday, WorcestershireYellow group was about Things that are yellowGreen group consisted of Building add-onsBlue group was of Concerns for a dentistPurple group items were difficult and can be classified as 'Words that seem longer written than spoken'The game with 4 groups is played by finding the common links between the connected words