| tonic |
| essence(noun, support, action, substance, idea) |
| feature(noun, adjective, special, specialty) |
| gist(noun, substance, idea, importance, meaning) |
| hallmark(noun, adjective, special, specialty) |
| characteristic(noun, adjective, special, specialty) |
| kernel(noun, substance, idea, importance, short) |
| theme(noun, substance, idea, subject, short) |
| topic(noun, point, line, substance, idea) |
| basis(noun, law, regulation, action, substance) |
| core(noun, support, action, substance, idea) |
| heart(noun, support, action, substance, idea) |
| key |
| keystone(noun, law, support, regulation, action) |
| minor |
| peculiarity(noun, specialty) |
| property(noun, specialty) |
| stamp(noun, specialty, prototype) |
| cachet(noun, specialty) |
| distinctive feature(noun, peculiarity) |