The term 'without warning' is used to describe something that happens SUDDENLY and unexpectedly. The crossword solutions for this term include 'ABRUPTLY' (8 letters), 'SUDDEN' (6 letters), 'SUDDENLY' (8 letters), 'ABRUPT' (6 letters), 'UNAWARES' (8 letters), 'allatonce' (9 letters), 'lastminute' (10 letters), 'PRECIPITOUS' (11 letters), 'allofasudden' (12 letters), and 'spurofthemoment' (15 letters). All of these words are synonyms for the phrase 'without warning, ' and they all refer to something happening SUDDENLY and without any prior notice.