bossboulder
nounUK /ˈbɒsˌbəʊldə/
US /ˈbɔsˌboʊldər/
A bossboulder is a very big rock that is in charge of the other rocks.
The kids climbed the bossboulder at the edge of the playground.
OTHER MEANINGS
2. The largest stone in a pile or group.
He saved the bossboulder for the bottom of the wall.
3. A pretend leader in a game about rocks.
In our game, the bossboulder tells the pebbles where to go.
4. A stubborn problem that is hard to move.
That math question was a real bossboulder for the whole class.