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Synonyms for Lukewarm (same or very similar meaning)

WordNet sense 1 (moderately warm):
tepid

WordNet sense 2 (having or producing a comfortable and agreeable degree of heat or imparting or maintaining heat):
warm

WordNet sense 3 (feeling or showing little interest or enthusiasm):
halfhearted, half-hearted

WordNet sense 4 (not enthusiastic; lacking excitement or ardor):
unenthusiastic


From the ODE community, based on WordNetadd/edit