ETYM Cf. French frangible.
Capable of being broken.
Easily broken, brittle.

ETYM Latin robustus oaken, hard, strong, from robur strength, a very hard kind of oak; cf. Skr. rabhas violence: cf. French robuste.
1. Physically strong.
2. Rough and crude.
3. Strong enough to withstand intellectual challenge.

1. Abounding in rocks or stones; SYN. bouldery, bouldered, stony.
2. Full of hardship or trials; SYN. rough.
3. Liable to rock

1. Of or pertaining to stone, consisting of, or abounding in, stone or stones; resembling stone; hard
2. Converting into stone; petrifying; petrific.
3. Inflexible; cruel; unrelenting; pitiless; obdurate; perverse; cold; morally hard