(18)
The term “student” means a person regularly pursuing a full-time course of study or training at an institution which is—
(A)
a school or college or university operated or directly supported by the United States, or by any State or local government or political subdivision thereof,
(B)
a school or college or university which has been accredited by a State or by a State recognized or nationally recognized accrediting agency or body.
(C)
a school or college or university not so accredited but whose credits are accepted, on transfer, by not less than three institutions which are so accredited, for credit on the same basis as if transferred from an institution so accredited, or
(D)
an additional type of educational or training institution as defined by the Secretary,
but not after he reaches the age of twenty-three or has completed four years of education beyond the high school level, except that, where his twenty-third birthday occurs during a semester or other enrollment period, he shall continue to be considered a student until the end of such semester or other enrollment period. A child shall not be deemed to have ceased to be a student during any interim between school years if the interim does not exceed five months and if he shows to the satisfaction of the Secretary that he has a bona fide intention of continuing to pursue a full-time course of education or training during the semester or other enrollment period immediately following the interim or during periods of reasonable duration during which, in the judgment of the Secretary, he is prevented by factors beyond his control from pursuing his education. A child shall not be deemed to be a student under this chapter during a period of service in the Armed Forces of the United States.