a tepid response: UNENTHUSIASTIC, apathetic, half-hearted, indifferent, cool, lukewarm, uninterested.
tep‧id /"tepÂd/
a feeling, reaction etc that is tepid shows a lack of excitement or interest [= lukewarm]:
a tepid response from the audience.
معنی سست هم داره ، یعنی بی علاقه و بی تفاوتی، سستی