Assertion: penguin's feather | /r/HasProperty | stiff
Facets:
Source sentences:
text: They also have feathers, which are comparatively short and stiff when compared to other birds.
text: The feathers of a penguin are relatively short and stiff in comparison to those of other birds, and they overlap closely to form a thick, smooth layer which traps air beneath it and so provides insulation from the cold.