-소

Etymology
Ultimately from, which gradually came to have an addressee-honoring meaning. Compare, , from the same suffix and both now with addressee-honoring meaning.

First attested for the imperative mood in the late sixteenth century. It expanded to the declarative and interrogative moods in the eighteenth century. However, it is not clear if the two suffixes are related.

The early imperative suffix was invariably, as in modern Gyeongsang. There are many theories about its etymology, but the most widely accepted one is that it is shortened from  + :



For the declarative and interrogative suffixes, there are again many theories:


 * Directly from the imperative suffix.
 * Equivalent to + :
 * > unattested *-쇠 (Yale: *-swoy) >
 * From the Early Modern polite suffix via intermediary ; this is also ultimately from.

The form is after sonorants because Middle Korean  was  in such environments, and Middle Korean  was subsequently deleted.

Usage notes

 * The semi-formal style is nowadays not commonly used in South Korea outside written commands, such as test questions or warnings, and literature. It is still popular in North Korea, although young women even there prefer the polite style.
 * In South Korea, it tends to have a dialectal connotation because the decline of the suffix and its related speech levels is less severe outside the Seoul area.
 * Standard Korean speakers are often confused or even offended by dialectal forms such as Hamgyong or the related Gyeongsang, because they tend to associate the suffix with a degree of self-assertiveness and hence lack of politeness.


 * After vowels, the liquid consonant, and the copula stems, Standard Korean uses the allomorph ; in the southern dialects of Gyeongsang and Jeolla, this becomes with a semivowel to break hiatus between vowels.
 * However, there are certain differences between these two largely allomorphic forms, especially regarding the imperative mood. In Standard Korean, only can be used for the imperative; after a consonant, the form  is used instead of . Conversely, in Gyeongsang Korean, only  can be used for the imperative, even if the stem ends in a vowel.


 * In Standard Korean, can always be replaced by, although it is less common. As mentioned above, however,  is obligatory for the imperative.