The paper aims at exploring some of the conditions and ways in which LSP (Language for Special Purposes) adult learners perceive misleading vocabulary. Specifically, the paper represents an attempt to find out whether adult learners of English who know the meaning of certain words can or cannot work out the new meaning of phrases or collocations that would result from the combination of two or more words. The phrases and/or collocations used in this study were conceptualised in sentences to show or mirror our learners’ ability in working out their collocational new meanings. First, individual general words (not technical) were taught and then a combination of two or more of these words (to give specific meanings) was worked out by 80 LSP learners through context. Second, after testing the same learners in these words and grading their responses, both descriptive and inferential statistics were used to indicate both frequencies and statistical significance levels.