What is "fortition"

Fortition \For*ti"tion\, n. [See Fortuitous.] Casual choice; fortuitous selection; hazard. [R.]

No mode of election operating in the spirit of fortition or rotation can be generally good.
--Burke.

n. 1 (context linguistics English) A sound change in which a consonant becomes more fortis. 2 (context obsolete English) casual choice; fortuitous selection; hazard

Fortition is a consonantal change from a 'weak' sound to a 'strong' one, the opposite of the more common lenition. For example, a fricative or an approximant may become a stop (i.e. becomes or becomes ). Although not as typical of sound change as lenition, fortition may occur in prominent positions, such as at the beginning of a word or stressed syllable; as an effect of reducing markedness; or due to morphological leveling.