Duniter specific

smith: Someone who is given the power to forge blocks.

forging blocks: Other blockchains say mining blocks because this action is generally rewarded by monetary creation (metaphor with gold mining). But because Duniter unique monetary creation is UD, we chose an other metaphor.

Substrate specific

validator: A validator node is a node configured to add blocks to the blockchain. By extension, validators are people holding the keys of these nodes.