What does "straight" mean?

Additional senses

1. 2.There are many several sorts of crooked lines, but there is only one which is straight. Dryden.
2. 3.(Bot.) Approximately straight; not much curved; as, straight ribs are such as pass from the base of a leaf to the apex, with a small curve.
3. 4.(Card Playing) Composed of cards which constitute a regular sequence, as the ace, king, queen, jack, and ten-spot; as, a straight hand; a straight flush.
4. 5.Conforming to justice and rectitude; not deviating from truth or fairness; upright; as, straight dealing.
5. 6.Unmixed; undiluted; as, to take liquor straight. [Slang]
6. 7.Making no exceptions or deviations in one's support of the organization and candidates of a political party; as, a straight Republican; a straight Democrat; also, containing the names of all the regularly nominated candidates of a party and no others; as, a straight ballot. [Political Cant, U.S.] Straight arch (Arch.), a form of arch in which the intrados is straight, but with its joints drawn radially, as in a common arch. -- A straight face, one giving no evidence of merriment or other emotion. -- A straight line. "That which lies evenly between its extreme points." Euclid. "The shortest line between two points." Chauvenet. "A line which has the same direction through its whole length." Newcomb. -- Straight-way valve, a valve which, when opened widely, affords a straight passageway, as for water. walk the straight and narrow.
7. 8.In a straight manner; directly; rightly; forthwith; immediately; as, the arrow went straight to the mark. "Floating straight." Shak. I know thy generous temper well; Fling but the appearance of dishonor on it, It straight takes fire, and mounts into a blaze. Addison. Everything was going on straight. W. Black.
8. 9.A hand of five cards in consecutive order as to value; a sequence. When they are of one suit, it is calles straight flush.
9. 10.To straighten. [R.] A Smith.