Words ending with 'nen'

I haven't written anything about the noun types, so let's start from somewhere. Just like Finnish has verb types, we also have noun types. That matters when you have to add an ending after a word, because sometimes the word stems change. I've written about the four important verb forms before.  I'd say that these are the four important noun forms that are worth memorizing by heart:

• nominative suomalainen: Minä olen suomalainen. - I am Finnish.
• genitive suomalaisen: Tänään on suomalaisen musiikin päivä. - Today (8.12.) is the Finnish music's day, the day of Finnish music.
• partitive suomalaista: Älä pakota minua kuuntelemaan suomalaista musiikkia. - Don't force me to listen to Finnish music.
• plural partitive suomalaisia: Onko sinulla suomalaisia kavereita? - Do you have Finnish friends? 

Once you know the genitive, just drop the n and add the ending you need.

• essive: Pidätkö itseäsi suomalaisena? - Do you consider yourself Finnish?
• elative: Tykkäätkö suomalaisesta ruoasta? - Do you like Finnish food? 

With plural, you also have to put an i between the word stem and the ending. Sometimes the i will cause the previous vowel to change or disappear. (And certain plural forms can be even trickier.)

• adessive: Miksi suomalaisilla hevibändeillä on niin paljon faneja Saksassa ja Etelä-Amerikassa? - Why do the Finnish heavy bands have so many fans in Germany and South America?

All the nationalities, some colours and a lot of adjectives end with nen. Here's my random list of words that belong to this group:

• nainen, ihminen, lautanen, lapanen - a woman, a human being, a plate, a mitten
• punainen, sininen, keltainen, valkoinen - red, blue, yellow, white
• iloinen, surullinen, onnellinen, erikoinen, erityinen,  tyytyväinen, viimeinen - glad, sad, happy, exceptional, particular, content, the last
• kreikkalainen, mongolialainen, ghanalainen, kongolainen - Greek, Mongolian, Ghanaian, Congolese

Also, if you make a verb into a noun, it ends with nen.

• leipoa > Leipominen on hauskaa! - Baking is fun!
• siivota > Vihaan siivoamista. - I hate cleaning.
• imuroida > Tykkäätkö imuroimisesta? - Do you like vacuuming?