Amateurish, unprofessional, unpolished, juvenile.
Of inferior quality.
A professional sports association at the lower levels of minor league organization.
A low-ranking or inferior level among groups, professions, organizations, etc.
Of or pertaining to a semiprofession.
Paid as a professional but on a part-time basis.
Of close to professional standard; prosumer.
A semiprofessional person.