gruesome /ˈɡɹuːsəm/adjective 3forms 4phrases 1 adjective3 •Repellently frightful and shocking; ghastly, horrific.He taks a svvirlie, auld moss-oak, / For some black, grousome Carlin; […] — 1785 •(informal) Awful, terrible.The team was so unprepared that the way it played was just gruesome. •(no longer used, rare) Of a person: filled with fear; afraid, fearful. formsgruesomer · more gruesome · gruesomest · most gruesome Phrases with gruesome gruesome twosomeA pair of people who go together, such as two friends, siblings, a married couple, etc., especially if they are mischievous, cause trouble, do not get along well, or have an unpleasant appearance.