Guinness is a popular Irish beer brand that has been around since 1759. The crossword solutions for the term 'Guinness Adjective' are 'LARGEST' (7 letters), 'FIRST' (5 letters), 'OLDEST' (6 letters), 'Fastest' (7 letters), and 'WETTEST' (7 letters). These adjectives accurately describe the Guinness brand, as it is the LARGEST brewery in Ireland, the FIRST to be established in Dublin, the OLDEST beer brand in the world, the fastest growing beer brand in Europe, and the WETTEST beer in the world.