thrift·less \-tlə̇s\adjective Etymology: Middle English thriftles unsuccessful, not prosperous, from thrift + -les -less 1.: lacking usefulness or worth < what thriftless sighs — Shakespeare > 2.: incapable of frugal management : wasteful of money or resources : improvident < a thriftless character who never knew where his next meal was coming from > • thrift·less·lyadverb