The term 'SIBILANT SIGNAL' is a combination of two words: 'SIBILANT' and 'SIGNAL'. SIBILANT refers to a type of speech sound characterized by a hissing or whistling sound, while SIGNAL refers to a gesture or action that conveys meaning. The two crossword solutions for this term are 'PSST' (4 letters) and 'PST' (3 letters). PSST is an interjection used to get someone's attention without alerting others, while PST is an abbreviation for the phrase 'please stand by'. Both of these terms are used to indicate a SIBILANT SIGNAL, either to get someone's attention or to indicate that someone should wait.