UKC

At what size does a cliff, crag, buttress become a boulder?

At Stanage, 8 feet. In the Alps, 30 feet. In the Himalayas, 60 feet

If you twist your ankle when you fall off its a boulder, if you break your ankle when you fall off its a crag. 

On Ben Nevis, over 600 feet! 

Multi pitch bouldering 

I don't think it's anything to do with size - they are simply two different things. A cliff (crag, buttress etc) is formed through glacial or fluvial erosion, earthquake, landslip, weathering etc and is 'attached' to the land, while a boulder usually comes from bits breaking off a cliff (though sometimes transported a long way from the cliff as an erratic) and sits 'on' the land.

Whenever a bit drops off any of the three former, it becomes one of the latter

Tradiation.  Boulders in Font are often bigger and scarier than Crags on grit.

Try some of the Bishop 'boulders' for size.....😊

Tradiation - is that a kind of 5G thing?

Or is it rays emitted by trad routes?

It is a podgy fingered typo, but it's actually a great looking word, isn't it ?

certainly would on a Tshirt

T'radiation?  What t'radiators pump out in t'North. Wazzocks the lot o' ye ....

In the States I got used to US climbers being most interested in hearing about grit as the unique feature of our climbing, and often commenting along the lines of "You Brits are so bold..." Then I visited Bishop and found myself highballing stuff that would have made two pitches at The Roaches!