pikkuhiljaa 
MEANING:
Adverb: Little by little, gradually.
Comes from pikku- (“little”) + hiljaa (“slowly”).
Used in a sentence: Alan pikkuhiljaa hermostua means ”I’m gradually getting irritated.”
MEANING:
Noun: plug (electric connecting device)
Comes from pisto (“sting, prick”) + tulppa (“plug”).
MEANING:
Noun: socket, outlet, wall socket; point (UK); receptacle, wall plug (US) (opening for connecting an electric plug)
MEANING:
Noun: bruise or contusion
Comes from mustelmilla = black and blue
You may also see sinelmä
MEANING:
Noun: otter (animal like the one pictured)
MEANING:
Noun: eyelash
Comes from silmä (“eye”) + ripsi (“lash, eyelash”)
You will also see simply ”ripsi” meaning the same.
MEANING:
Noun: cash (money in the form of notes or coins)
EXTRA CREDIT:
Used in a sentence:
Maksatteko käteisellä vai luottokortilla?
nastakengät
MEANING:
Noun: Studded shoes
DERIVED FROM:
Comes from nasta, which means ”thumbtack,” ”pin,” ”stud” (as in studded tires) or ”tack.” And kengät (”shoes.”)
You will also see nastarenkaat (studded tires), though normally just referred to as nastat.
EXTRA CREDIT:
In slang, nasta also means cool, neat, or great. Though the origin of that slang is not clear.