What does "thwart" mean?

Additional senses

1. 2.Thwartly; obliquely; transversely; athwart. [Obs.] Milton.
2. 3.Across; athwart. Spenser. Thwart ships. See Athwart ships, under Athwart.
3. 4.A seat in an open boat reaching from one side to the other, or athwart the boat.
4. 5.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.
5. 6.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.
6. 7.To move or go in an oblique or crosswise manner. [R.]
7. 8.Hence, to be in opposition; to clash. [R.] Any proposition . . . that shall at all thwart with internal oracles. Locke.