If it’s word grammar you need, you can always rely on Tim Bowen to give you a straight answer.
The word straight functions as an adjective, a verb and occasionally as a noun.
As an adjective, apart from meaning not bending or leaning, it can also be used to mean honest and true, as in ‘He wouldn’t give me a straight answer’, or correct, as in ‘Let me get this straight – your wife was driving at the time’. Only used in prenominal position, straight can also mean happening one after the other without interruption, as in ‘This is their sixth straight win’, and serious, as in ‘Sorry, but I just can’t keep a straight face’.
As an adverb, straight can be used to refer to a particular period of time, again without interruption, as in ‘We’d been driving for five hours straight and needed a break’. If you cannot see straight or think straight, you cannot see or think clearly, as in ‘She was too tired to think straight’. If criminals go straight, they give up a life of crime and begin to lead an honest life.
The adverbial phrase straight off means immediately, as in ‘You should have told him straight off that we couldn’t afford it’. The phrase straight out has a similar meaning but has the added meaning of directly or bluntly, as in ‘She asked me straight out if I wanted the job’.
As both a noun and an adjective, (a) straight can be used to mean someone who is normal and ordinary but slightly boring, as in ‘He’s a bit (of a) straight’, or someone who is attracted to people of the opposite sex, as in ‘It’s a gay club but straights are welcome’ or ’He’s straight but his best friend is gay’.
It is also used in the expression the straight and narrow, meaning the right and moral way to behave, as in ‘He’s making a real effort to get back on the straight and narrow’.