Wiktionary
a. (context medicine English) Of a blood type within the ABO and Rh blood grouping system. Blood type '''A positive''' has a phenotype of "A" and a Rhesus system classification of positive.
Wikipedia
"A Positive" is a 1998 horror short story by Kaaron Warren.
Usage examples of "a positive".
This is what you might call the all-purpose pentagram - drawn this way it always has a positive influence.
By language alone are we enabled to submit it to a positive test: the letter is the ballast of the mind, the body which allows it to act, and in acting to scatter the unreal delusions of dream.
This could give space-time a positive curvature that would not allow travel into the past.
Since electrons carry a negative electric charge, atoms that lose them possess a positive charge, and those that gain them possess a negative one.
I was relieved at his presence, which was a positive deliverance for me, for what could I have said to Versilov?
There is still the very real consequence of bringing shame on the family, although this is not as important as it once was, since today non-marital sexual experience is seen with a positive attitude among many of the parents' peer group.
Now I found a clean cut in it about three inches long -- not a mere scratch, but a positive cut.
For now, most of the exterior of the suit has a mild negative charge, balanced by a positive one on the inner surface.
On the whole he would be happier if Liz could prove a negative instead of a positive.
Josh could not be certain whether this was a positive, negative, or opinion-withheld reaction.