Choose your preferred definition

In a previous post, I've already complained about the undefined definition of the word "actinomycete". Today I might even weep a little.

Using Dictionary.com and Reference.com as sources, I've learnt that an actinomycete can be understood as a bacterium belonging to:

• order Actinomycetales [1,2,3,4], or
  
• phylum Actinobacteria [5,6], or
  
• phylum Chlamydobacteriae, or order Actinomycetales [7], or
  
• genus Actinomyces, or family Actinomycetaceae, or order Actinomycetales [8]

But don't put the blame on dictionary writers. There isn't a unified definition for "actinomycete" since the word lost its status as a class in bacterial nomenclature, long time ago. Anyway, dictionaries are really entertaining, aren't they?

[1] The American Heritage® Dictionary of the English Language, Fourth Edition.
[2] WordNet® 3.0.
[3] Merriam-Webster's Medical Dictionary.
[4] Crystal Reference Encyclopedia.
[5] The American Heritage® Science Dictionary.
[6] Wikipedia, the free encyclopedia.
[7] Dictionary.com Unabridged (v 1.1).
[8] The American Heritage® Stedman's Medical Dictionary.

Definitions retrieved on July 17, 2007, from Dictionary.com website [1,2,3,5,7,8] and from Reference.com website [4,6].

(Dictionary image created at Hetemeel.com. I used a scanning electron micrograph of aerial mycelium and spore of Streptomyces coelicolor; credits: Mark Buttner, Kim Findlay, John Innes Centre)