Pseudomonas aeruginosa

Etymology
Pseudomonas aeruginosa:

pseudo: "false" (from greek ψευδο (pseudo), meaning "false")

monas: "unit" (from greek μονος (monos), meaning "single unit")

Instead of unit, monas more likely refers to the nanoflagellate "Monas", which Pseudomonas spp. resembles (source: http://wwwnc.cdc.gov/eid/article/18/8/et-1808_article.htm).

aeruginosa: "greenish-blue" (from latin aerūgō, meaning "rusted copper", which takes on a greenish-blue colour).

Explanation
The bacteria Pseudomonas aeruginosa was likely named as such because while it looks like the nanoflagellate Monas, which is a protist, in terms of both its size and its movement, it is not Monas, so is "false" (pseudo). In culture, Pseudomonas aeruginosa looks greenish-blue (aerugo).

Synonyms
P. aeruginosa