Dictionary

Definitions of bitch:

• an unpleasant difficulty; "this problem is a real bitch"
• cunt: a woman who is thoroughly disliked; "she said her son thought Hilary was a bitch"
• gripe: informal terms for objecting (bitching); "I have a gripe about the service here"
• backbite: say mean things (bitch about)
• female of any member of the dog family

Explain

The word bitch — originally used for the female members of the canid species, specially dogs — is more often employed in a figurative sense as an insult for a promiscuous woman, or a malicious, spiteful, domineering, intrusive, and/or mean person.

The former specialized meaning is retained and in widespread use among dog aficionados and breeders, but derogatory usage has become so prevalent in the last century that the term has acquired a profane connotation.
A girl who is both detested and respected. The following witticism well exemplifies what is meant when one says bitch, "A slut will sleep with anyone, while a bitch will sleep with anyone but you."

Definitions of bastard:

• asshole: insulting terms of address for people who are stupid or irritating or ridiculous
• the illegitimate offspring of unmarried parents
• born out of wedlock; "the dominions of both rulers passed away to their spurious or doubtful offspring"- E.A.Freeman
• derogatory term for a variation that is not genuine; something irregular or inferior or of dubious origin; "the architecture was a kind of bastard suggesting Gothic but not true Gothic"
  bogus: fraudulent; having a misleading appearance
• Any sweetened wine, but more correctly applied to a sweet Spanish wine (white or brown) made of the bastard muscadine grape.
• A file (a tool) which has a coarse cut
• A child born out of wedlock. Under common law, if the parents later married one another, the child was legitimatised. At the request of the mother or the authorities, an identified father could be compelled to provide for the child’s support. Note that a bastard child, even if acknowledged, could not inherit from the father. of unusual make or proportions

Explain

"Tthe great Australian endearment" (eg. Come and have a drink with me, ya bastard!), but can also be used as

An insult; interpreted according to context.Properly the base child of a father of gentle or noble birth, but more generally, any illegitimate childs.

A child born out of wedlock. Something that is of irregular, inferior, or dubious origin.
Slang. A person, especially one who is held to be mean or disagreeable.
Born of unwed parents; illegitimate. Not genuine; spurious: a bastard style of architecture.
Resembling a known kind or species but not truly such. Born to parents who are not married to each other: baseborn, illegitimate, misbegotten, natural, spurious, unlawful.