A hyphen can be and often is used when a prefix is added to a word (pre-test), but the compound term can instead be closed (pretest).

How do you spell post test?

an achievement test administered after a course of instruction.

What is the root word of pretest?

Entries linking to pretest word-forming element meaning “before,” from Old French pre- and Medieval Latin pre-, both from Latin prae (adverb and preposition) “before in time or place,” from PIE *peri- The Latin word was active in forming verbs. … Sometimes in Middle English muddled with words in pro- or per-.