grin /ɡɹɪn/verb 4noun 2forms 5phrases 2 verb4 •To smile, parting the lips so as to show the teeth.Why do you grin? Did I say something funny? •To express by grinning.She grinned pleasure at his embarrassment. •To grin as part of producing a particular facial expression, such as a smile or sneer.He grinned a broad smile when I told him the result.He grinned a cruel sneer when I begged him to stop. •(old-fashioned) To show the teeth, like a snarling dog.The pangs of death do make him grin. — 1591 noun2 •A smile in which the lips are parted to reveal the teeth.When the ceremony was finished a wide grin broke across his face, and it was that grin she saw, relieved and happy all at once. — 1997 •(no longer used) A snare; a gin. formsgrinned · grinning · grinneth · grins · grinnest Phrases with grin grin and bear itTo endure a difficult or disagreeable situation with good humor. shit-eating grinA broad smile indicating self-awareness that may suggest self-satisfaction, smugness, discomfort, or embarrassment.