**According to Cassels Wörterbuch "Except in the ligatures ch, ck and sch this [the letter c] is not a genuine German letter, and occurs only in foreign borrowings. it is now normally replaced by a k"
Club (club)
clever (clever)
charmant (charming)
chaotisch (chaotic)
charismatisch (charismatic)
campen (to camp)
Chamäleon (chameleon)
Charakter (character)
Christin (Christian)
Christentum (Christianity)
Chor (chorus, choir)
China (China)
Chemiker (chemist)
Chemie (chemistry)
"Chef" is a false cognate, meaning boss, not chef.
"Champignon" comes directly from the French, and is one way to say mushroom.
Circa (Approximately), Codiert (Coded) Chiffreschrift (Cipher) Creme (cream), Cyankali (Cyanide), I'm sure there are more
Some words that start with G and end with Y are:gabbygalaxygalleygaudygaygenealogygentlygeographygeologygeometryghastlyghostlygigglygiddygingerlyglorygoodygoofygorygraduallygravellygravelygravitygravygraygreedygullygummyguppyGuy
adageappendagearrangeaveragebadgebaggagebargebridgebudgebulgecabbagecagecarriagechangedamagedangerdrainagefoliagefootagegarage (second g)heritagehomagehostageimageluggagemarriagemiragepackagepagepledgepostageridgesagespillagespoilagestagestrangestoragetriagevillagevintagevoyage
Gitta
German or Gaelic
There aren't any true German words that start with X. They all come from different languages (mostly ancient Greek)
Some German words that start with the letter O are Opa, Oma and oberflächlich.
giddyup
Good
gniazdo
goal
gag
gay