It means " a very small proportion of the whole".
From the Bible, Isaiah
40:15 (King James
"Behold, the nations are as a drop of a bucket, and are counted as the
small dust of the balance: behold, he taketh up the isles as a very
'A drop in the bucket' is the predecessor of 'a drop in the ocean',
which means the same thing. This is first found in a piece from The
Edinburgh Weekly Journal, July 1802:
"The votes for the appointment of Bonaparte to be Chief Consul for
life are like a drop in the ocean compared with the aggregate of the
population of France."
drop in the bucket"是从"a
drop in the ocean"而来的；这两个词组的意思是一样的。