Thwart, v. t. [imp. & p. p. Thwarted; p. pr. & vb. n. Thwarting.]
1. To move across or counter to; to cross; as, an arrow thwarts the air. [Obs.] Swift as a shooting star In autumn thwarts the night. Milton.
2. To cross, as a purpose; to oppose; to run counter to; to contravene; hence, to frustrate or defeat. If crooked fortune had not thwarted me. Shak. The proposals of the one never thwarted the inclinations of the other. South.
5 other Webster entries under this spelling
Thwart, a.
1. Situated or placed across something else; transverse; oblique. Moved contrary with thwart obliquities. Milton.
2. Fig.: Perverse; crossgrained. [Obs.] Shak.
Thwart, adv.
Thwartly; obliquely; transversely; athwart. [Obs.] Milton.
Thwart, prep.
Across; athwart. Spenser. Thwart ships. See Athwart ships, under Athwart.
Thwart, n. (Naut.)
A seat in an open boat reaching from one side to the other, or athwart the boat.
Thwart, v. i.
1. To move or go in an oblique or crosswise manner. [R.]
2. Hence, to be in opposition; to clash. [R.] Any proposition . . . that shall at all thwart with internal oracles. Locke.
Shades of meaning
Fernald has no entry of its own for thwart; he lists it under hinder.
He lists it without comment; the entries above explain its neighbors.