series vs subspecies

series

noun
  • A subdivision of a genus, a taxonomic rank below that of section (and subsection) but above that of species. 

  • A set of consonants that share a particular phonetic or phonological feature. 

  • A television or radio program which consists of several episodes that are broadcast in regular intervals 

  • A number of things that follow on one after the other or are connected one after the other. 

  • An unranked taxon. 

  • A parcel of rough diamonds of assorted qualities. 

  • The sequence of partial sums ∑ᵢ₌₁ⁿa_i of a given sequence aᵢ. 

  • A group of matches between two sides, with the aim being to win more matches than the opposition. 

subspecies

noun
  • A rank in the classification of organisms, below species. 

  • A taxon at that rank, often indicated with trinomial nomenclature (such as Felis silvestris silvestris in zoology and Pinus nigra subsp. salzmannii in botany). 

  • A subdivision of a species in other scientific disciplines. 

How often have the words series and subspecies occurred in a corpus of books? (source: Google Ngram Viewer )