Correct spelling

senior

Correct spelling, explanation: this word comes directly from Latin (also senior), meaning older. The word hasn’t been changed in any way in English, it is a direct loanword. Therefore seniour or any other change in spelling is incorrect. The only correct form is senior.

Definition of senior:
adjective, of a higher competence or older
He doesn’t have enough experience to become a senior manager.
noun, somebody older than another, usually in family (father-son relation); in school: a student in their last year or final class
James is a senior in our family; James Jr is his son.


Incorrect spelling

seniour

Incorrect spelling, explanation: seniour is a misspelling, probably made due to the fact, that -or in American English is often written as -our in British English. This word, senior, is however a Latin loanword, and it is spelled exactly like in Latin. Therefore senior is the only correct form.

Incorrect spelling

seinor

Incorrect spelling

Incorrect spelling

sennior

Incorrect spelling

Incorrect spelling

senoir

Incorrect spelling