酸っぱい

Etymology
First cited to a text from 1823.

This appears to be a compound of.
 * The suffix -ppai may be related to more neutral suffix.
 * Alternatively, the suffix may represent a reanalysis of the -ppai ending in adjective, where the ending derives from . While there are historically attested examples of shoppai evolving from shio + hayushi (the classical form), where  first appears in the late 1500s, there are no such attestations for the more recent word suppai.

Adjective

 * 1)  sour