shock

1 shock /ˈʃɑːk/ noun
plural shocks
1 shock
/ˈʃɑːk/
noun
plural shocks
Britannica Dictionary definition of SHOCK
1 
a  [count] : a sudden usually unpleasant or upsetting feeling caused by something unexpected — usually singular
— often + of
— see also culture shock, sticker shock
b  [count] : something unexpected that causes a sudden usually unpleasant or upsetting feeling — usually singular
c  [noncount] : a state in which you are experiencing a sudden usually unpleasant or upsetting feeling because of something unexpected
d  [count] : a sudden bad change in something
2 
[noncount] medical : a serious condition in which the body is not able to get enough blood to all the parts of the body
◊ Shock is caused by a severe injury, a large loss of blood, etc.
— see also shell shock, toxic shock syndrome
3 
[count] : the effect of a strong charge of electricity passing through the body of a person or animal — usually singular
5 
: a violent shake
[count]
— often + of
[noncount]

a shock to the/your system

: something that has a sudden and usually unpleasant effect on you
2 shock /ˈʃɑːk/ verb
shocks; shocked; shocking
2 shock
/ˈʃɑːk/
verb
shocks; shocked; shocking
Britannica Dictionary definition of SHOCK
1 
[+ object] : to surprise and usually upset (someone)
— often used as (be) shocked
— often + at or by
— often + into
2 
: to cause (someone) to feel horror or disgust
[+ object]
[no object]

— shocked

adjective
3 shock /ˈʃɑːk/ adjective
3 shock
/ˈʃɑːk/
adjective
Britannica Dictionary definition of SHOCK
always used before a noun
— used to describe something that surprises and usually upsets people

shock horror

British, informal
— used to say that you are surprised by something unpleasant or upsetting when you really are not
4 shock /ˈʃɑːk/ noun
plural shocks
4 shock
/ˈʃɑːk/
noun
plural shocks
Britannica Dictionary definition of SHOCK
[count]
: a thick and full mass of hair — usually singular