flimsy

American Heritage® Dictionary of the English Language, Fourth Edition

1. adj. Light, thin, and insubstantial: a flimsy fabric.
2. adj. Lacking solidity or strength: a flimsy table.
3. adj. Lacking plausibility; unconvincing: a flimsy excuse.
4. n. Thin paper usually used to make multiple copies.
5. n. Something written on this thin paper.

Century Dictionary and Cyclopedia

1. Without material strength or solid substance; of loose and unsubstantial structure.
2. Without strength or force of any kind; weak; ineffectual: as, a flimsy argument.
3. Synonyms Unsubstantial, thin, slight.
4. Feeble, trivial, shallow, superficial, frivolous, foolish, puerile.
5. n. A thin sort of paper by means of which several copies of a writing may be made at once; transfer-paper.
6. n. A bank-note, from its being made of thin paper.
7. n. A manifold copy of a report or despatch made on flimsy; reporters' ‘copy’; a duplicate or a triplicate writing made on flimsy.

Wiktionary

1. adj. Likely to bend or break under pressure; weak, shaky, flexible, or fragile.
2. n. Thin typing paper used to make multiple copies

GNU Webster's 1913

1. adj. Weak; feeble; limp; slight; vain; without strength or solidity; of loose and unsubstantial structure; without reason or plausibility.
2. n. Thin or transfer paper.
3. n. A bank note.

WordNet 3.0

1. adj. lacking solidity or strength
2. n. a thin strong lightweight translucent paper used especially for making carbon copies
3. adj. lacking substance or significance
4. adj. not convincing