fastshell
nounUK /ˈfɑːstʃel/
US /ˈfæstʃel/
A fastshell is a hard outer cover that helps something move quickly.
The little turtle had a smooth fastshell that let it slide over the rocks.
OTHER MEANINGS
2. A computer program that runs commands very quickly.
He typed a command into the fastshell and the job finished in a second.
3. A protective case designed for speed and lightness.
The bike's fastshell kept the gears safe without slowing it down.
4. A nickname for someone who is quick and tough on the outside.
Our coach calls the new runner Fastshell because nothing slows her down.