c. 1600, from Late Latin susceptibilis "capable, sustainable, susceptible," from Latin suscept-, past-participle stem of suscipere "to take, catch, take up, lift up; receive, admit; submit to; sustain, support, bear; acknowledge, accept," from sub "up from under" (see sub-) + capere "to take," from PIE root *kap- "to grasp." Susceptive in the same sense is recorded from early 15c. Related: Susceptibly.
word-forming element making abstract nouns from adjectives and meaning "condition or quality of being ______," from Middle English -ite, from Old French -ete (Modern French -ité) and directly from Latin -itatem (nominative -itas), suffix denoting state or condition, composed of -i- (from the stem or else a connective) + the common abstract suffix -tas (see -ty (2)).
Roughly, the word in -ity usually means the quality of being what the adjective describes, or concretely an instance of the quality, or collectively all the instances; & the word in -ism means the disposition, or collectively all those who feel it. [Fowler]
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Harper, D. (n.d.). Etymology of susceptibility. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/susceptibility