I would define a Pawn as a piece of which you start with many, and has a value so low that they act merely as 'change' when other pieces of unequal type are traded.
Irreversibility or promotability IMO are not requirements. E.g. when a chess variant fills the second rank of the setup with pieces that move and capture like an inverted Y (fWbF), I think most people would consider those 'Pawns'.
Large Shogi variants tend to have multiple piece types of very low value. (But the Asian Pawn is significantly weaker than a Shatranj Pawn too.) E.g. a Shogi Knight (fN), Stone General (fF), or Go-Between (vW). People don't consider those Pawns, though, (even though they of course all promote in Shogi, and the first two are irreversible), because you only start with a pair of them.
I would define a Pawn as a piece of which you start with many, and has a value so low that they act merely as 'change' when other pieces of unequal type are traded.
Irreversibility or promotability IMO are not requirements. E.g. when a chess variant fills the second rank of the setup with pieces that move and capture like an inverted Y (fWbF), I think most people would consider those 'Pawns'.
Large Shogi variants tend to have multiple piece types of very low value. (But the Asian Pawn is significantly weaker than a Shatranj Pawn too.) E.g. a Shogi Knight (fN), Stone General (fF), or Go-Between (vW). People don't consider those Pawns, though, (even though they of course all promote in Shogi, and the first two are irreversible), because you only start with a pair of them.