1. in a way that is thin, light, or insubstantial in construction or material
2. in a way that lacks strength, conviction, or credibility; weakly or unconvincingly

Examples

• The tent was flimsily constructed and could not withstand the storm.
• She flimsily defended her argument with vague references and no real evidence.
• The old bridge was flimsily built and needed immediate repair.
• He flimsily excused his absence with an unconvincing story.
• The fabric was flimsily woven and tore easily.
• The case against him was flimsily based on circumstantial evidence.