Noun

(head)

(alga)

Noun

(algae)

(biology) Any of many aquatic photosynthetic organisms, whose size ranges from a single cell to giant kelps and whose form is very diverse; some are eukaryotic and some prokaryotic; includes the seaweeds.

Noun

(en-noun) (wikipedia virus) (Virus)

(archaic) Venom, as produced by a poisonous animal etc.

(pathology, microbiology, virology) A submicroscopic, non-cellular structure consisting of a core of DNA or RNA surrounded by a protein coat, that requires a living host cell to replicate, and often causes disease in the host organism.

* {{quote-magazine, year=2013, month=May-June, author= Katie L. Burke

, title= In the News , volume=101, issue=3, page=193, magazine=(American Scientist) , passage=Bats host many high-profile viruses that can infect humans, including severe acute respiratory syndrome and Ebola.}}

* 2001 , Leslie Iversen, Drugs: A Very Short Introduction (Oxford 2001, p. 64)

Viruses are the smallest and most simplified forms of life.

A disease caused by these organisms.

(computing) A program which can covertly transmit itself between computers via networks (especially the Internet) or removable storage such as CDs, USB drives, floppy disks, etc., often causing damage to systems and data; also computer virus.