[1525–35; a-1 + build + -ing2]This word is first recorded in the period 1525–35. Other words that entered Englishat around the same time include: converter, folio, mask, secure, shufflea- is a reduced form of the Old English preposition on, meaning “on,” “in,” “into,” “to,” “toward,” preserved before a noun in a prepositionalphrase, forming a predicate adjective or an adverbial element (afoot; abed; ashore; aside; away), or before an adjective (afar; aloud; alow), as a moribund prefix with a verb (acknowledge), and in archaic and dialectal use before a present participle in -ing (set the bells aringing); and added to a verb stem with the force of a present participle (ablaze; agape; aglow; astride; and originally, awry); -ing is a suffix forming the present participle of verbs (walking; thinking), such participles being often used as participial adjectives (warring factions)