highschool
n. C / Un. the school you go to when you are a teenager, usually between the ages of 14 and 18. It is the final stage of school before you go to university or start working.
n. a secondary school typically comprising grades nine through twelve. Often used as a modifier before another noun.
She is a student at the local highschool.
After finishing middle school, most students in the district attend the same highschool for four years.
The transition from a small private academy to a large public highschool proved challenging for the student, who was unaccustomed to such a diverse and fast-paced environment.
Often written as two words ('high school') in formal American English; the single-word form is a common variant. When used as a modifier, it precedes the noun (e.g., 'highschool sweetheart').
I am in the highschoolI am in highschoolWhen referring to one's status as a student, the definite article is usually omitted in American English.