Appendix:Korean sound symbolism

Modern Korean has a somewhat productive ideophonic ablaut process opposing "yin" and "yang" vowels. In modern Korean, these are primarily used for ideophones and sensory terms (e.g. color words). They were significantly more productive in Middle Korean (and presumably earlier forms), and have left a significant trace in the modern language even though most Koreans are no longer aware of them.

If Middle Korean lost some of the productivity of ablaut, it as a replacement innovated a productive system of consonant alternations based on a distinction between lenis, fortis, and aspirated consonants. Forms with fortis consonants are more intensifying than ones with lenis ones, and forms with aspirated consonants even more so.

Vowels
The Korean ablaut system coincides with its vowel harmony system. Middle Korean vowel harmony, which governed the phonological shape of most native MK morphemes and the allomorphy of many verbal suffixes and most case- or topic-marking noun particles, took the following form (digraphs excluded):

Vowel harmony became weakened due to vowel shifts, particularly the conditioned merger of to  word-internally and to  word-initially. Harmony is now vestigial, largely consisting of an opposition in the allomorphy of certain verbal suffixes. Note that the featural nature of the Hangul script makes the correspondences clearly visible:

In both Middle and Modern Korean, verbs with "neutral" vowels take yin-vowel suffixes.

Semantic ablaut is more productive today than the harmonic system, involving a far wider range of vowels. All pairs ultimately derive from the Middle Korean oppositions. For instance, Middle Korean opposed ; regular phonological change merged the former into  and the latter into, explaining how an originally neutral vowel participates in the ablaut process.

With a few exceptions, the system only works for purely native words, not Sino-Korean and especially modern English loans.

Nuances
The yin-vowel form is dark/murky, and the yang-vowel form is bright/clear:

The yin-vowel form is heavy/loud/big, and the yang-vowel form is light/quiet/small:

The yin-vowel form is dull/thick, and the yang-vowel form is sharp/thin:

The yin-vowel form is unpleasant, and the yang-vowel form is pleasant:

The yin-vowel form is intense, and the yang-vowel form is less so:

The yin-vowel form is old, and the yang-vowel form is young:

The yin-vowel form is damp, and the yang-vowel form is dry:

In many cases (perhaps the majority), one form is normal and the other form is marked or rare.

Historical ablaut pairs
Ablaut was significantly more productive in Middle Korean. MK ablaut pairs not necessarily identifiable as such in Modern Korean include:

There are more controversial suggestions, including vs., which would at least fit semantically.

In certain words, the MK form varied freely between the ablaut pairs, but either one was chosen in Modern Korean, or the two forms came to have different meanings.

Consonant alternation
Modern Korean distinguishes lenis, fortis, and aspirate consonants:

The fortis forms are considered intensive, while the aspirate ones are para-intensive:



A tripartite division is not necessarily the most common; often, the aspirate form is missing, producing a bipartite division between a non-intensive lenis form and an intensive fortis form. For many forms, the lenis forms have become unusual and the default form is the fortis one.

This sort of emphatic fortition of the consonant is quite common in modern Korean slang, e.g. >.