1.NounAny one of several species of small herring which are commonly preserved in olive oil or in tins for food, especially the pilchard, or European sardine (Sardina pilchardus, syn. Clupea pilchardus). The American sardines of the Atlantic coast are mostly the young of the Atlantic herring and of the menhaden.
"They feasted on premium sardines packed in olive oil, as did their hunting dogs, who insisted on joining the meal."
2.NounSomeone packed or crammed into a small space.
"They watched bemused as countless sardines disgorged from a railway car that was never designed to hold so many passengers."