fi-

fi- is moral disgust welded onto the front of a word. Homo gives fihomo, a scoundrel; afero gives fiafero, a shady business; vorto gives fivorto, a swear word; besto gives fibesto. The root keeps its ending and its part of speech.

The prefix is the interjection fi, the noise of disapproval, pressed into service. That interjection owns the plain slug on this site, which is why this page sits at fi- with the hyphen showing.

The trap is a field of decoys. Fidela, fidi, fiera, fingro, fini, fiksi and firma merely start with those two letters; none carries a grain of the prefix.

Set it against -aĉ-. A domaĉo is a badly built house. A fidomo is a house where something wicked goes on.