What is the meaning of -소?

Used in the semi-formal style, a register in which the speaker acknowledges the listener's high status without conceding their own:

  1. Marks the declarative mood.

    Marks the declarative mood.

    Marks the interrogative mood.

    Marks the imperative mood; the form is 으오 (-euo) in Standard Korean and (-so) in Gyeongsang.

    Used in the 허씨요체 style, a general polite speech level used e.g. when addressing one's parents or a stranger on the street, or when talking to a social inferior in formal contexts:

    1. Marks the declarative mood.
    2. Marks the interrogative mood.

    Marks the declarative mood.

    Marks the interrogative mood.

    Used in the 허소체 style, a speech level denoting emotional intimacy, used e.g. when addressing one's wife or speaking to one's family members:

    1. Marks the imperative mood.

    Marks the imperative mood.

    Used in the formal polite style:

    1. Marks the declarative mood.
    2. Marks the interrogative mood.
    3. Marks the imperative mood.

    Marks the declarative mood.

    Marks the interrogative mood.

    Marks the imperative mood.

    Source: wiktionary.org