parabiosis

noun

1. (countable, uncountable)The (natural or surgical) union of parts of two organisms, especially in such a way as to cause them to share their vascular systems. Organisms so joined then are called parabionts.

   “Parabiosis is the condition of more than one living organism joined ..., with ... circulatory fluids being exchanged among the parabionts.”

   “2017 Cosima in "Manacled Slim Wrists", Orphan Black Mud, parabiosis means that he is processing young blood and transfusing it.”

2. (countable, uncountable)The fusion of two embryos to form conjoined twins

   “Conjoined identical twins... could be thought of as parabionts.”

3. (countable, uncountable)A transient physiological state of suspension of obvious vital activities such as to enable an organism to escape the notice of its enemies or to conserve its energy.
4. (countable, uncountable)A form of symbiosis, typically among ants, in which different species share common nest galleries but maintain distinct broods and do not practice mutualism other than incidentally.
5. (countable, uncountable)An alien form of life within an organism, commonly invasive, such as a growing cancer.

   “1873, Walter Moxon, Guy's Hospital Reports, 3rd series, Vol XVIII https://archive.org/details/3reportsguy18guysuoft …the fever sperm coming into ... the living frame ... is able to create a sort of other life or parabiosis within it ....”