Q. The plural of curriculum is curricula. Why does the dictionary list symposiums as an acceptable plural for symposium? And does the rule differ for every plural of words ending in -um?

A. Curricula is the plural in Latin. In American English, the plural is curriculums. Both are correct, although in academic writing, there is a tradition of using the Latin plurals. Chicago editors follow Merriam-Webster when forming plurals of adopted words, but please see CMOS 7.6.