Noah Webster's Dictionary (a.) Moderately warm; neither cold nor hot; tepid; not ardent; not zealous; cool; indifferent.

Multi-Version Concordance Lukewarm (1 Occurrence) Revelation 3:16 So, because you are lukewarm, and neither hot nor cold, I will vomit you out of my mouth. (WEB KJV WEY ASV DBY YLT NAS RSV NIV)