without a bend, angle, or curve; not curved; direct

a straight path.

exactly vertical or horizontal; in a perfectly vertical or horizontal plane

a straight table.

(of a line) generated by a point moving at a constant velocity with respect to another point.

evenly or uprightly formed or set

straight shoulders.

without circumlocution; frank; candid

straight speaking.

honest, honorable, or upright, as conduct, dealings, methods, or persons.

Informal . reliable, as a report or information.

right or correct, as reasoning, thinking, or a thinker.

in the proper order or condition

Things are straight now.

continuous or unbroken

in straight succession.

thoroughgoing or unreserved

a straight Republican.

supporting or cast for all candidates of one political party

to vote a straight ticket.

unmodified or unaltered

a straight comedy.

without change in the original melody or tempo

She does straight songs, with just the piano backing her.

Informal .

heterosexual.

traditional; conventional.

free from using narcotics.

not engaged in crime; law-abiding; reformed.

undiluted, as whiskey.

Theater . (of acting) straightforward; not striving for effect.

Journalism . written or to be written in a direct and objective manner, with no attempt at individual styling, comment, etc.

She gave me a straight story. Treat it as straight news.

Cards . containing cards in consecutive denominations, as a two, three, four, five, and six, in various suits.

in a straight line

to walk straight.

in an even form or position

pictures hung straight.

in an erect posture

to stand up straight.

directly

to go straight to a place.

without circumlocution; frankly; candidly (often fol. by out ).

honestly, honorably, or virtuously

to live straight.

without intricate involvement; not in a roundabout way; to the point.

in a steady course (often fol. by on )

to keep straight on after the second traffic light.

into the proper form or condition; in order

to put a room straight.

in possession of the truth or of true ideas

I want to set you straight before you make mistakes.

sold without discount regardless of the quantity bought

Candy bars are twenty cents straight.

Journalism . directly and objectively

Write the circus story straight.

without personal embellishments, additions, etc.

Tell the story straight. Sing the song straight.

(of liquor) served or drunk without ice, a mixer, or water; neat

He drank his whiskey straight.

the condition of being straight.

a straight form or position.

a straight line.

a straight part, as of a racecourse.

Informal .

a heterosexual.

a person who follows traditional or conventional mores.

a person who is free from narcotics.

Chiefly Games . a succession of strokes, plays, etc., which gives a perfect score. ?

go straight

Informal . to live a law-abiding life; no longer engage in crime.

play it straight, Informal . to do something without jokes, tricks, subterfuge, distortions

or the like

a comedian who plays it straight when he crusades against drug abuse.

straight off

without delay; immediately

I told him straight off what I thought about the matter. Also, straight away.

straight up

(of a cocktail) served without ice

a gin martini straight up.