it depends what you mean by the bottom part.... are you talking about the stem, roots, ect?
The top part of a wave is called the crest, while the bottom part is called the trough.
The bottom of the food chain is the plant or the producer.
The bottom part of a cake is called the base.
Denominator. The top part is called the numerator.
Hem.
a Hull
a bottom (body part) is called 'un derrière' (masc.) in French
The part of the potato plant we eat is called the tuber, which is actually an enlarged underground stem.
The bottom part of your hand is the Palmar sideand the top part is the Dorsal side.
well the leaves the mini dots at the bottom part of it does the job
its called a lowbret
They're called udders. :-)