In Loglan parlance, the word "lexeme" means "cmavo class" (more generally, "class of terminals in the parser", "class of words that can be interchanged and leave the sentence with the same grammar" — so cmene and brivla are considered lexemes.)
This conflicts with the linguistic jargon usage, which means "lexical entry". In other words, "boy", "boys", "boy's" and "boys'" are four different word forms, but one and the same lexeme.