Describes something that is not clearly expressed, understood, or defined; often used for statements, meanings, or outlines. Relatively formal and somewhat literary.
His explanation was obscure, and I couldn't understand what he wanted to say.
この契約書の条項は不文明な表現が多い。
Many clauses in this contract are expressed in unclear language.
曖昧 means 'vague' or 'ambiguous' and is more everyday; 不文明 is stronger and more formal, implying something is not just vague but poorly articulated or obscure.
A variant spelling of 不分明 “unclear, indistinct,” with the same reading ふぶんめい.