The term 'REALLY BUG' can be defined by six crossword solutions: NETTLE (6 letters), EXASPERATE (10 letters), IRK (3 letters), RANKLE (6 letters), RILE (4 letters), and EATAT (5 letters). All of these words refer to the act of annoying or irritating someone, and they all have similar meanings. NETTLE means to cause slight pain or discomfort, EXASPERATE means to make someone very angry or frustrated, IRK means to annoy or bother someone, RANKLE means to cause irritation or resentment, RILE means to make someone angry or upset, and EATAT means to bother or irritate someone. Together, these words provide a comprehensive definition for the term 'REALLY BUG'.