frith-

Etymology
From, from the verbal nouns of Old Irish verbs like , , with the initial preverb , from  (compare 🇨🇬, prefix ), from the zero grade of  (compare 🇨🇬).

Prefix

 * 1) anti-, counter-
 * 2) back
 * 1) back

Etymology
From (compare 🇨🇬, prefix ), from the zero grade of  (compare 🇨🇬).

Prefix

 * 1) counter-, beside, against

Usage notes
There are three basic shapes of the prefix, used in the following manner:
 * Frith- proper manifests as such before morpheme-initial vowels.
 * Fris- and fres- tend to appear before resonants. Originally fres- was created by a following vowel lowering the vowel in older fris-, but by Old Irish times the two variants were interchangeable.
 * Fre- and fri- were used before stops. Like with fris- and fres-, the distribution of these two variants originally depended on whether the following morpheme caused its original -i- to lower to -e-, but by the Old Irish period this distribution was not strictly followed. It triggered no mutation of the next morpheme in line.
 * Fris- and fres- tend to appear before resonants. Originally fres- was created by a following vowel lowering the vowel in older fris-, but by Old Irish times the two variants were interchangeable.
 * Fre- and fri- were used before stops. Like with fris- and fres-, the distribution of these two variants originally depended on whether the following morpheme caused its original -i- to lower to -e-, but by the Old Irish period this distribution was not strictly followed. It triggered no mutation of the next morpheme in line.

Later on, the non-frith- forms became fossilized as frith- overtook the other shapes in productivity. Frith- also caused lenition of the initial consonant of a following morpheme as this happened. For instance,.

Etymology
From.

Prefix

 * 1) by-, sub-
 * 2) counter-