The words: stub, nitty-gritty, meat, core, inward, sum, gist, heart and soul, substance, center, kernel, essence, heart, root, and marrow are all considered synonyms for the word 'nub'. The word nub itself is used as a noun and has been defined as (1) the crux or central point of a matter or (2) as a small lump or protuberance.

In a sentence, nub can be used as follows. What do you think is the nub (crux/heart) of our problem? People usually ask this type of question when they want to try to resolve a problem or conflict that they are facing.

After noting the meaning of the word tendril, it is clear that it is not a synonym for the word 'nub'. The word tendril mostly refers to a slender threadlike appendage of a climbing plant, often growing in a spiral form, that stretches out and twines around any suitable structure which can be used as a support. The main purpose of tendrils is to support the plants.

More Info: www.synonyms.net