• (n. pl.) An artificial group of passerine birds having slender bills, as the humming birds.
Ten`u·i·ros'tres noun plural [ New Latin ] (Zoology) An artificial group of passerine birds having slender bills, as the humming birds. 
Tenuirostres (slender-beaked) is a section of the Insessores order of birds containing those species with a long slender, tapering beak.
tenuirostral, tenuirostres Thin-billed; applied to birds with a slender bill; such as, humming birds.