Try Our Apps


Avoid these words. Seriously.


[ri-ket-see-uh] /rɪˈkɛt si ə/
noun, plural rickettsiae
[ri-ket-see-ee] /rɪˈkɛt siˌi/ (Show IPA),
[ri-ket-see-uh z] /rɪˈkɛt si əz/ (Show IPA)
any member of the genus Rickettsia, comprising rod-shaped to coccoid microorganisms that resemble bacteria but can be as small as a large virus and reproduce only inside a living cell, parasitic in fleas, ticks, lice, and mites and transmitted by bite to vertebrate hosts, including humans, causing such severe diseases as typhus and Rocky Mountain spotted fever.
any rickettsia or rickettsialike microorganism of the orders Rickettsiales and Chlamydiales.
Origin of rickettsia
1915-20; < New Latin, after Howard T. Ricketts (1871-1910), U.S. pathologist; see -ia
Related forms
rickettsial, adjective Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
Cite This Source
British Dictionary definitions for rickettsia


noun (pl) -siae (-sɪˌiː), -sias
any of a group of parasitic bacteria that live in the tissues of ticks, mites, and other arthropods, and cause disease when transmitted to man and other animals
Derived Forms
rickettsial, adjective
Word Origin
C20: named after Howard T. Ricketts (1871–1910), US pathologist
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Cite This Source
Word Origin and History for rickettsia

parasitic organism, 1919, named 1916 in Modern Latin by H. da Rocha-Lima in honor of U.S. pathologist H.T. Ricketts (1871-1910), who first identified it in 1909 and died of typhus as a result of his contact with it. The bacteria causes typhus and Rocky Mountain spotted fever, but is unrelated by pathology or etymology to rickets (q.v.), which is the result of vitamin D deficiency. The surname is a development from Rickard, variant of Richard, or else from the diminutive form Ricot.

Online Etymology Dictionary, © 2010 Douglas Harper
Cite This Source
rickettsia in Medicine

Rickettsia Rick·ett·si·a (rĭ-kět'sē-ə)
A genus of gram-negative bacteria that are carried as parasites by many ticks, fleas, and lice and cause diseases such as typhus, scrub typhus, and Rocky Mountain spotted fever.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
Cite This Source

Word of the Day

Nearby words for rickettsia

Word Value for rickettsia

Scrabble Words With Friends