Definition of annulation in US English:

annulation

noun

Zoology
  • See annulate

    • ‘It is characterized by a very gently tapered, finely laminated conical tube lacking strong transverse annulations.’
    • ‘The inner and outer tube surfaces are very smooth, without any indication of segmentation, annulation, or collaring.’
    • ‘The annulations give the shell a segmented appearance.’
    • ‘At the same time, both genera have well-developed, multiannulate first antennae, whereas modern branchiopods have dwarfed first antennae without much of annulation or segmentation at all.’
    • ‘The annulation is weakly developed along the surface opposite to the attached portion.’

Pronunciation

annulation

/ˌanyəˈlāSHən/