In biology, the receptacle is the swollen basal part of the flower. It can also be geared as the top of the stalk or pedicel. When the stalk of the plant, the part which connects flower to the plant, gets flattened and the other parts of the flower including the 4 whorls (calyx, corolla, androecium, gymnoecium) start, that flattened part is called the receptacle. It is the end part of the stalk or pedicel.
In some fruits like a strawberry, it is the thing that becomes the main fleshy edible part of the fruit. The fruit species, rubus, has a conical receptacle with a cluster of seeds (droplets) on top of it.
When a raspberry is picked, the receptacle gets separated from it but it is just the opposite case in blackberry where it remains attached.
In psychology, they are the structures at the end of the branches of algae mainly brown algae. There, they act as specialized structures having reproductive organs and also help in storage.