About
HSK levels

    1. son; child
    2. seed
    3. egg
    4. small thing
    5. 1st earthly branch: 11 p.m.–1 a.m., midnight, 11th solar month (7th December to 5th January), year of the rat
    6. viscount, fourth of five orders of nobility 五等爵位[wu3 deng3 jue2 wei4]
    7. ancient Chinese compass point: 0° (north)
    8. subsidiary; subordinate; (prefix) sub-

    他的儿子今年十岁了。 Tā de érzi jīnnián shí suì le.

    zi

    1. noun suffix, as in 椅子[yi3 zi5] "chair"