I thought it was every round of combat.
So the thief blocks 2 points of damage from a trap in round 1.
If still alive in Round 2, he blocks 2 more points of damage from the trap.
The example where he slaps the food out of the other character's hand is a multi-trap example. I think over two rounds.
Same for the cleric. X points of healing IF and ONLY IF monsters (and maybe ghosts) attacked that turn.
So the thief blocks 2 points of damage from a trap in round 1.
If still alive in Round 2, he blocks 2 more points of damage from the trap.
The example where he slaps the food out of the other character's hand is a multi-trap example. I think over two rounds.
Same for the cleric. X points of healing IF and ONLY IF monsters (and maybe ghosts) attacked that turn.