The word "in-most" refers to the innermost part of something. However, there are various synonyms that you can use instead of this word to convey the same meaning. Some of the popular synonyms include "innermost", "deep-seated", "core", "central", "deepest", "most profound", "fundamental", "essential", "heart", "soul", and "intimate". Each of these synonyms has a slightly different connotation but can be used interchangeably with "in-most". Whether you're writing an academic paper or a creative piece, using synonyms can add variety to your writing and make it more interesting for your readers.