• Webster's Revised Unabridged Dictionary
    • n Pterylosis (Zoöl) The arrangement of feathers in definite areas.
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Century Dictionary and Cyclopedia
    • n pterylosis The arrangement or disposition of ptilosis; the plumage of a bird, considered with reference to the manner in which the feathers are implanted in the skin in definite pterylæ; the mode of feathering; the distribution of the feathers in tracts. It differs from ptilosis in that the latter relates to the character of the plumage itself, not to its disposition upon the body.
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Webster's Revised Unabridged Dictionary
NL., fr. NL. & E. pteryla,