Informal; chiefly North American usage meaning ‘directly; exactly’, often in the phrase “plunk in the middle”.
The cabin sits plunk in the middle of the woods.
La cabane se trouve pile au milieu des bois.
Onomatopoeic use to represent the sound of something dropping or striking.
plocOnomatopée imitant un bruit bref de chute ou de pincement. "Plunk!" went the pebble as it hit the water.
"Ploc !" fit le caillou en frappant l’eau.