OSX: Stop autocorrect splitting words
Navigate to System Preferences > Keyboard > Text > Correct Spelling Automatically (uncheck)

If you wish to leave autocorrect on, but create certain exceptions, you can alternatively leave it checked and in the same pane add, for example:

Replace: infoclass 
With: infoclass 

This sets up an exclusion of sorts so that autocorrect does not change it to info class