Abounded, swarmed (6)
I believe the answer is:
teemed
I believe this is a double definition.
'abounded' is the first definition.
(I've seen this before)
'swarmed' is the second definition.
('teem' can be a synonym of 'swarm')
(Other definitions for teemed that I've seen before include "(Of rain) poured down" , "Swarmed, was very plentiful" , "Swarmed or poured" , "Swarmed or pured down" , "Was swarming (with)" .)