кошка /koshka/ female
кот /kot/ male, 
котёнок, sg котята pl are kittens,

a cat in general (of unspecified sex) is feminine form.

мяу /miau/ is how we imitate the sound; мяукать, a verb, to meow; мяукание/мяуканье a verbal noun. (These aren't used for cries prodiced by cats on amourous occasions).

Мурлыкать, мурчать to purr.
Мур - an interjection used to denote this sound (i wouldn't call it 'imitation')

кис-кис[-кис- etc.] is the way to call a cal, to attract attention.

брысь! - get away!

There also exist
киса /keesa/-
Well, it is not exactly diminutive or childish language... but is often used in similar situations.
киска - a most common and neutral (i.e. just a noun, not necessary affective) diminutive  of this.

Some simple-minded translators used this toi translate 'pussy' in its obscene meaning. Shame on them. Sometimes i meet girls who occasionaly use it this way.
I don't like it, as киска denotes 'a cat' pretty specificaly, precisely and unambiguosly. Its etymology and sound are different...

There are tons of affective diminutive forms (used to address, not just as nouns... except with childs):
кисочка, кисонька, кисуля, кисуня...

As to the latter group... Recently I noticed that the Finnish word for 'a cat' is "kissa". Now i'm curious: who borrowed it from whom? Both directions are possible.

<em>Chinese: 貓 (mao)

</em>Alexandra, 貓, in reformed 'simplified' CHinese orthography 猫 is fun and easy to memorize character. 
Left part (radical) would denote among other things  'a small animal'. And indeed, it is exactly a small animal is drawn her. It is a clear pictogram. The right part (phonetic) points on the reading 'miao' (in Mandarin).

The character reads 'mao' in Mandarin (with a different tone than Chairman Mao), and other ways, including more close to the Western meow, in other dialects.<em>
</em>

Hungarian: macska (collective noun), kandúr (male cat), cica (young cat or fondling)

In Dutch cat is kat. Like said already.

Furthermore I can add that a female cat is called poes. (Pronounced exactly like the first syllabil of the English word Pussy)

A male cat is called kater. (Pronounced like more or less like cat with 'uhr' put behind it, though the a is longer than in cat. Like the a in ma and pa.)

A young cat, that is a loan word from English I think. It is exactly the same word: Kitten.

In Serbian- мaчкa.