WordNet sense 1 (an area that is approximately central within some larger region):

center, eye, middle, centre

WordNet sense 2 (a positive feeling of liking):

affection, fondness, tenderness, warmheartedness, warmness, affectionateness, philia

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

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

WordNet sense 4 (the locus of feelings and intuitions):

bosom

WordNet sense 5 (the hollow muscular organ located behind the sternum and between the lungs; its rhythmic contractions move the blood through the body):

pump, ticker

WordNet sense 6 (the courage to carry on):

mettle, nerve, spunk

WordNet sense 7 (an inclination or tendency of a certain kind):

spirit