Ancient Roman coins
'ancient roman coins' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for denarii that I've seen before include "money from abroad" , "Bits" , "A lot of asses" , "Ancient Roman coins" , "22 [COINS]" .)
(Other definitions for sesterces that I've seen before include "Old money" , "Roman brass" .)