| inner(adjective, inside, interior, inward) |
| internal(adjective, inside, interior, inner, inward) |
| inward(adjective, inside, interior, inner, inward) |
| inwardness |
| main(adjective, lead, head, master, boss) |
| mass(noun, organization, strength, material, effect) |
| mean(noun, adjective, average, center, middle) |
| mid(adjective, middle) |
| nuts and bolts(noun, expression, idiom, good, understanding) |
| sense(noun, strength, point, burden, substance) |
| sine qua non(noun, expression, idiom, importance, heart) |
| stuff(noun, good, quality, understanding, cause) |
| average(noun, adjective, middle) |
| bottom line(noun, expression, good, understanding, spirit) |
| bulk(noun, material, mass, matter, whole) |
| burden |
| cardinal(noun, adjective, lead, head, master) |
| center of gravity(expression, idiom) |
| centrum(noun, center, middle, target) |
| corpus(noun, organization, area, body, strength) |