Definition of "plantkin"

In this remarkable disease, the ordinary precursor and companion of contagious typhus, he managed to find in the blood during an exacerbation, a minute plantkin, moving and swinging in very rapid vibration, the spirochaete which vanishes again along with the disease.

1879, Rudolf Ludwig Karl Virchow, Infection-diseases in the Army

Still more was I surprised through another occurrence of this same plantkin.

1885, Publications of the Massachusetts Homoeopathic Medical Society

Some people were definitely fucking around: One blog, run by a "social justice warrior plantkin" who obsessively demands that their followers check their species privilege, was clearly a hoax.

2016 August 4, Callie Beusman, “'I Look at a Cloud and I See It as Me': The People Who Identify As Objects”, in Broadly

As a demisexual plantkin I can't stand how white privileged transgendered people are acting as if they're the vanguard of the trans movement.

2015 September 4, Michelle Steiner, “Caitlyn Jenner on Ellen: Marriage equality views have evolved since transitioning”, in Entertainment Weekly

No, sorry, but Jared is plantkin, though he's still searching to narrow it down.

2017, Bryant A. Loney, Take Me to the Cat, page 190