It is generally accepted that collocation is essential for establishing synonymy. They are related linguistic features which are important and useful for language learners. Given this importance, this present study considered the experience of 120 Thai English as a Foreign Language (EFL) students. The study explored the students' knowledge of academic collocation and synonymy in relation to their academic experience at university and examined their justifications for their collocation selections. The results of a forced-choice collocation test revealed that while the majority of the students demonstrated their knowledge of academic collocations and synonyms, the more experienced (ME) students significantly outperformed their less experienced (LE) counterparts in most collocation questions. In terms of explanations for their collocation choices, the ME group referred to their encounters as the most frequent reason while the LE group made the largest number of guesses. The findings suggest that despite not being taught explicitly about academic collocations, EFL learners can develop their collocation repertoire incidentally as they are exposed to academic discourse over their university years.