screw

1 screw /ˈskruː/ noun
plural screws
1 screw
/ˈskruː/
noun
plural screws
Britannica Dictionary definition of SCREW
[count]
1 
: a narrow, pointed metal cylinder that has a wide flat or rounded top and a ridge (called a thread) that goes around it in a spiral
◊ A screw is used to hold things together or to attach things. It is inserted into wood, metal, etc., by being turned.
— see picture at carpentry; compare 1nail 1
2 
: an object that has a thread like a screw which is used to attach or connect it to something — usually used before another noun
3 
informal + offensive
a  : an act of sexual intercourse
b  : a sexual partner
4 
slang : a prison guard

have a screw loose

informal or have a loose screw
: to be crazy

put the screws on/to (someone or something)

informal
: to use force or the threat of force to make (someone or something) do what you want

tighten the screws

informal
: to put more pressure on someone or something to do something
2 screw /ˈskruː/ verb
screws; screwed; screwing
2 screw
/ˈskruː/
verb
screws; screwed; screwing
Britannica Dictionary definition of SCREW
1 
always followed by an adverb or preposition, [+ object] : to attach (something) with a screw
2 
always followed by an adverb or preposition
a  [+ object] : to turn (something) so that it attaches or connects to something
b  [no object] : to fit onto or into something by being turned
3 
informal + offensive
a  [no object] : to have sex
b  [+ object] : to have sex with (someone)
4 
[+ object] informal
a  : to take something from (someone) by lying or breaking a rule
— often + out of
b  : to prevent (someone) from having or getting something that is deserved or expected — often + out of or (US) over
5 
[+ object] informal + impolite — used to express anger, disgust, etc.
6 
[+ object] : to press or squeeze (something) so that it is no longer flat or smooth — often + up

have/get your head screwed on right/straight

— see 1head

screw around

[phrasal verb] chiefly US, informal
1 
: to do things that are not useful or serious : to waste time
2 
: to have sex with someone who is not your husband, wife, or regular partner
— often + with
3 
: to use or do something in a way that is not very serious
— often + with
4 
screw around with (something) : to handle or play with (something) in a careless or foolish way

screw up

[phrasal verb] informal
1 
a  : to make a mistake : to do something incorrectly
b  screw (something) up or screw up (something) : to make a mistake in (something)
2 
screw (something) up or screw up (something) : to damage or ruin (something) : to damage or change (something) so that it does not work properly
3 
screw (someone) up or screw up (someone) : to make (someone) very upset and unhappy for a long time
4 
screw (something) up or screw up (something) : to tighten the muscles of (your face or eyes)
5 
screw up the/your courage : to make yourself brave enough to do something difficult
— see also 2screw 6