http://www.biology.iupui.edu/biocourses/n100/2k4ch39repronotes.html
It is human. You can even call it a human being if you want. It's certainly alive. However, the fact remains that these stages need to be gone through, after which it is generally accepted as being a complete human being. The point is, the process is a gradual one.
Look at the picture for day 15-21. It has a neural tube. It says these will become brain and spinal column IN THE FUTURE.
At this stage, it has no heart, no brain, no spine, no legs, no eyes, no feelings, no emotions. It DOES have a tail, a neural groove, somites, and pharyngeal arches. It is like the plan of a house....and later, more like the foundations. The raw materials are missing....the mother will supply these gradually over the nine months, turning that blueprint into a house. You can point to the plan and say "this is where the kitchen will be" but you don't yet have a house. It's not legally a house, and you can't shelter in it. It isn't "a house".
If abortions are going to take place (and they are, legal or not) then I'd prefer they happened at this point or before in a safe environment....rather than later....(as the foetus becomes more and more human) in an unsafe illegal environment.
The morning after pill should be supported by all who dislike abortion.
You failed to find a definition of a human being that fits a foetus, real life.
One more question....how old are you? Do you reckon that from the date of your birth....or your date of conception?