The present study investigated the change in meaning and the correlation between the derivatives derived from the base of adjectives, saya, soyo, and sawa found through contemporary Japanese literature from ancient times.
Saya, the adjectival base which had an audiovisually “sei (brisk, cleanliness)” image in KOJIKI and NIHON-SYOKI, used to be the semantic equivalent of sawa.. Sawa, however, had a stronger auditory nuance than saya. As the verb sawaku was derived from it, the adjectival base started to be used mainly as a verb.
Soyo is also a word that principally had the same auditory nuance as sawa in MANYO-SYU. For example, in the HEIAN period, soyo was frequently used as a rhetorical device KAKEKOTOBA in WAKA, and soyo-soyo was established as a word referring to the “sound of leaves occurring due to a breeze.” This usage is distinct from saya-saya, which refers to a very weak sound that occurs regardless of wind. During the EDO period, sawaku (again, derived from the adjectival base sawa) produced an onomatopoeia depicting the noisy sound zawa-zawa. Therefore, saya-saya, depicting weak sounds, and sawa-sawa, depicting strong and noisy sounds, eventually formed a pair relationship.
On the other hand, the adjective took on the visual image of “cleanliness” rather than the onomatopoeia. More specifically, the adjective derived from the adjectival base saya came to mean “to be upright.” The “uprightness” here also means “there is no obstacle or opacity.” The meaning “completely without worries” derived from “uprightness” is present in adjectives derived from sawa, such as sawaraka and sawayaka. After the pre-modern period, however, the representative word referring to the “uprightness,” sayaka, went out of use, and sawayaka evolved to mean “uprightness.” In other words, sayaka and sawayaka became semantically closer.