1. dual
2. duality
3. antithesis
4. coupled phrases (as rhetorical device)
5. spouse

1. nature
2. character
3. property
4. quality
5. attribute
6. sexuality
7. sex
8. gender
9. suffix forming adjective from verb
10. suffix forming noun from adjective, corresponding to -ness or -ity
11. essence

classifier: 個