It is a human, it's a human fetus. It's not a completely developed human though. According to the definition, it is a baby.
fetus:
Noun
Inflected forms: pl.fe·tus·es 1. The unborn young of a viviparous vertebrate having a basic structural resemblance to the adult animal. 2. In humans, the unborn young from the end of the eighth week after conception to the moment of birth, as distinguished from the earlier embryo.
baby:
Noun
Inflected forms: pl.ba·bies 1. a. A very young child; an infant. b. An unborn child; a fetus. c. The youngest member of a family or group. d. A very young animal. 2. An adult or young person who behaves in an infantile way. 3. Slang A girl or young woman. 4. Informal Sweetheart; dear. Used as a term of endearment. 5. Slang An object of personal concern or interest: Keeping the boat in good repair is your baby.
Adjective
Inflected forms: bab·i·er, bab·i·est 1. Of or having to do with a baby. 2. Infantile or childish. 3. Small in comparison with others of the same kind: baby vegetables.
Transitive verb
Inflected forms: ba·bied, ba·by·ing, ba·bies To pamper like a baby; coddle. See Synonyms at pamper.
Whether or not it is murder is the actually issue. I don't believe abortion to be murder, but then again I don't believe killing defenseless animals to be murder either, that doesn't mean I think it's a good thing to go around shooting animals.