The compound 'species-level' is a modern scientific term formed by combining two nouns in a hyphenated adjectival structure. The first element, 'species', originates from Latin 'species', meaning "a particular sort, kind, or form," which itself derives from the Proto-Indo-European root spek- ("to observe"). This reflects the concept of a species as a distinct observable form. The second element, 'level', traces back to Latin 'libella', a tool for checking horizontality, metaphorically extended to mean a rank or tier. The compound logically builds its meaning by specifying that the scope or rank of analysis ('level') is that of the entire biological species ('species'), contrasting with other hierarchical levels in biological classification.

Structure: species (kind) + level (rank) - species: From Latin 'species' (appearance, kind, sort). Functions as the base noun, specifying the taxonomic rank. - level: From Latin 'libella', a diminutive of 'libra' (balance, scale). Functions as a noun used in a compound to denote a rank, plane, or standard of consideration.