The summit of an eminence.
"The climber reached the nab to admire the panoramic view from the mountain's highest point."
tag the base runner to get him out
"The shortstop moved quickly to nab the sliding runner before he could touch second base."
seize suddenly
"The security guard managed to nab the thief just as he reached for the cash register."
To seize, arrest or take into custody (a criminal or fugitive).
"The police managed to nab the suspect just as he was about to jump over the fence."
Initialism of National Australia Bank.
"The bank rejected our loan application because NAB has stricter lending criteria than other institutions in the region."