atonic /eɪˈtɒnɪk/adjective 4noun 1forms 3 adjective4 •unstressed •Lacking muscle tone. •Characterized by atony, or want of vital energy. •not having tone (pitch)Some syllables are distinguished by an absence of tone; they are said to be atonic or to have a neutral tone. — 1984 noun1 •(old-fashioned) A sound with lack of tone or vocality. formsatonics · more atonic · most atonic