Rat bastard derogatory slang countable noun
Used to describe a person who is extremely despicable, untrustworthy and immoral
I was foolish enough to believe a rat bastard like him!
He abandoned his wife and children when he became rich. He's really a rat bastard.
Used to describe someone immoral or perverse, having a tendency toward sexual promiscuity
To refer to a very unpleasant or sneaky person whose manner is not sincere or moral
One needs to understand the basic techniques or primary details of something before taking actions that require greater skills
Peter failed because he did not learn to walk before he ran.