noun
supplementary exam; makeup exam
An exam given to students who missed the original test due to illness or other valid reasons, or as a second chance after failing.
インフルエンザで期末試験を受けられなかったので、来週追試験があります。
I couldn't take the final exam because of the flu, so I have a makeup exam next week.
Compound of 追 (つい, 'follow-up' or 'supplementary') and 試験 (しけん, 'exam').