From an earlier *prasti, from *prat-ti, from Proto-Baltic *prat-, from Proto-Indo-European *pret-, *prot- (“to understand”). The first-person form is derived from a variant with an extra n, *prantuo, from *prantu, from protu. Up until the 17th century, prast basically meant “to understand,” “to perceive,” i.e., it was synonymous with saprast; the present-day meaning occurred alongside the older meaning and became dominant only by the end of the 19th century. Cognates include Lithuanian pràsti (“to get used to, to understand, to perceive”), Old Prussian issprestun (“to understand”) (compare Latvian izprast), Gothic 𐍆𐍂𐌰𐌸𐌾𐌰𐌽 (fraþjan, “to think, to recognize, to understand”), 𐍆𐍂𐌰𐌸𐌹 (fraþi, “mind, intelligence”), Latin interpres (“intermediary, mediator, interpreter”), Tocharian A pratim, etc.