WordNet sense 1 (considerable capital (wealth or income)):

means

WordNet sense 2 (what a communication that is about something is about):

content, message, content, subject matter

WordNet sense 3 (the choicest or most essential or most vital part of some idea or experience):

center, core, essence, gist, heart, kernel, marrow, meat, nitty-gritty, nub, pith, sum, inwardness, heart and soul

WordNet sense 4 (the idea that is intended):

meaning

WordNet sense 5 (that which has mass and occupies space):

matter