Gitaigo/Giongo

Gitaigo and giongo reference onomatopoetic words that are commonly used in Japanese.  Giongo is similar to the onomotopia found in the English language, where you a word is used to imitate a sound that's actually made.  We don't have gitaigo in English however, and it's by far one of the most charming parts of Japanese language and also one of the (for me at least) biggest barriers to proficiency since I find them to be really hard to memorize.

So, in Japanese, you use gitaigo words that are repeated in sets of two to describe things like states of emotions, physical conditions, sometimes actions and describing the states of objects.  I think this comes across as sounding kind of childish to someone who speaks English (it sounds kind of like babytalk or something), but it's not seen that way at all in Japan.  The differences between in meaning are often subtle (ex: there are at least 5 ways of expressing how people cry) which makes gitaigo a really useful, concise and very expressive way to speak

The few examples below were taken from a book I recently purchased called Giongo and Gitaigo  A Practical Guide to Mimetic Expressions through Pictures.

Words to express sleeping:
"uto uto" - dozing off outside of one's regular sleeping hours
"guu guu" - fast asleep (and snoring)
"suya suya" - sleeping peacefully like a baby

Words to express crying:
"ogyaa ogyaa" - the crying of a baby
"een een" - the loud crying of a child
"oi oi" - the loud crying of a mainly a man
"shiku shiku" - the quiet crying of a woman or child
"meso meso" - the whimpering of a crybaby

Words to describe textures:
"zara zara" - describes a surface which is rough due to small bumps, clinging sand, etc.
"tsuru tsuru" - smooth with a flat surface, very slippery
"gotsu gotsu" - hard with many surface irregularities, or something crude and unpolished
"fuwa fuwa" - something soft and light
"gunya gunya" - soft and malleable, twisted or bent