Primarily, the word marrow is being used for a substance that is present in the bones and is a fatty network of connective tissues that are present in the centre of bones. Sometimes the word is also being used to describe some kind of squash plants that people grow for the elongated fruit that can be got from them. These plants have the skin that is very smooth and also have the dark green colour and smoothness in it. The flesh of the fruit is completely white.
The word is also being used in the figurative sense and you can use it to describe about the most vital part of an idea or experience. In the expression 'the gist of the argument', you can replace the word 'gist' with marrow.
The word is also being used in the figurative sense and you can use it to describe about the most vital part of an idea or experience. In the expression 'the gist of the argument', you can replace the word 'gist' with marrow.