The term ‘freak’ generally refers to something that is unusual and/or unexpected.
The word freak can be used to refer to something or someone. If something occurs that is strange or unusual it considered to be a “freak accident.” Similarly if a person or animal has an unusual look, that person or animal is considered a “freak”. The term could be referencing an anomaly with their physical appearance or a different manner of speaking. It could also be related to the way that person is dressed.
Another usage of freak is when it is used to refer to something or someone that is behaving weirdly or differently that what they usually do, e.g. “Don’t freak out.”
The term is often also used in the manner of “freakish” or ‘freaky.” This refers to something that has a “freakish” manner, i.e. it does not generally behave normally. Something can also be “freaky,” i.e. something that is very strange or odd.
At times, freak is also used as a mild cuss word instead of “fucking.” E.g. “This is freaking cold.”