brittle

American Heritage® Dictionary of the English Language, Fourth Edition

1. adj. Likely to break, snap, or crack, as when subjected to pressure: brittle bones.
2. adj. Easily damaged or disrupted; fragile: a brittle friendship. See Synonyms at fragile.
3. adj. Difficult to deal with; snappish: a brittle disposition.
4. adj. Lacking warmth of feeling; cold: a reputation for being brittle and aloof.
5. adj. Brilliantly sharp, as in percussive sound.
6. adj. Perishable.
7. adj. Fleeting; transitory.
8. n. A confection of caramelized sugar to which nuts are added: walnut brittle.

Century Dictionary and Cyclopedia

1. 1. Fickle; changeable.
2. Breaking easily and suddenly with a comparatively smooth fracture, as glass; fragile; not tough or tenacious.
3. Figuratively, easily destroyed; perishable; fleeting.

Wiktionary

1. adj. Inflexible, liable to break or snap easily under stress or pressure.
2. adj. Not physically tough or tenacious; apt to break or crumble when bending.
3. adj. archaeology Said of rocks and minerals with a conchoidal fracture; capable of being knapped or flaked.
4. adj. Emotionally fragile, easily offended.
5. n. uncountable A confection of caramelized sugar and nuts.
6. n. uncountable Anything resembling this confection, such as flapjack, a cereal bar, etc.

GNU Webster's 1913

1. adj. Easily broken; apt to break; fragile; not tough or tenacious.

WordNet 3.0

1. n. caramelized sugar cooled in thin sheets
2. adj. having little elasticity; hence easily cracked or fractured or snapped
3. adj. lacking warmth and generosity of spirit
4. adj. (of metal or glass) not annealed and consequently easily cracked or fractured