late 15c., "to go through searchingly or in detail, run over with careful scrutiny," from Middle English per- "completely" (see per) + use (v.). Meaning "read carefully and critically" is by 1530s, but this could be a separate formation. Meaning "read casually" is from 19c. Related: Perused; perusing. "The formation looks unusual, but it is well supported by similar formations now obsolete, e.g. peract, perplant, perstand, etc." [Century Dictionary].
suffix forming nouns of action from verbs, mostly from Latin and French, meaning "act of ______ing" (such as survival, referral), Middle English -aille, from French feminine singular -aille, from Latin -alia, neuter plural of adjective suffix -alis, also used in English as a noun suffix. Nativized in English and used with Germanic verbs (as in bestowal, betrothal).
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Harper, D. (n.d.). Etymology of perusal. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/perusal