rock the boat and stone the crows

This week I've been pondering what makes a stone a stone, a rock a rock and a boulder a boulder. Or to put it another way, when does a stone become a rock? My first thoughts - size does matter. To my mind a stone is apple sized and smaller. A rock is bigger than an apple but smaller than pumpkin. Lets say a large pumpkin. And a boulder bigger than a pumpkin. But what does the dictionary say?

A stone n. is a piece of earthy or mineral matter, especially smaller than a boulder; a paving block; a gem; the central hard portion of a fruit; a unit of weight equal to 14lbs. It is also - according to the dear dictionary - a rock.

On the other hand, a rock n. is a large mass of stone or stony material; a boulder; a gem; a firm or solid foundation; a cylindrical stick of coloured and flavoured sweet.

So hold on, a rock is a mass of stone AND a boulder?

A boulder n. is a large mass of stone or rock; a climbing route small enough to tackle without ropes; a town in Colorado. (Strictly speaking Boulder not a boulder for that last one)

So according to the dictionary, a stone is smaller than a boulder and is also a rock. A rock is a boulder or a mass of stone. Whereas a boulder is a large mass of stone or rock.

Hello confusion my old friend.

The closer we look, the deeper down the rabbit hole we go as stone and rock are verbs as well as nouns. To rock means to move rhythmically back and forth (He rocked the baby to sleep) and to disturb or upset (the revelations about the will rocked the whole family) How can one word have two almost contradictory meanings?

The conclusion I make from all this confusion is that words - like rocks - are weighty. They can mean a multitude of things depending on where they are hefted or placed.

But you knew that already - right?

P.S. And on the rocks means both likely to fail AND served on ice.