Definition from Wiktionary, the free dictionary
- Used to denote substandard degree, lack of quality, or inferiority.
- Unlike most Esperanto suffixes, -aĉ- does not have an inherent part of speech, but rather inherits the part of speech of the stem to which it is suffixed.
- The difference between fi- and -aĉ- is similar, but not identical, to the difference between evil and bad in English. fi- always denotes low morality, while -aĉ- always denotes low quality.