An immature feather, before the veins have expanded and while the shaft is full of fluid.
More example sentences
- Changes in the physical structure of the pin feather during growth may be the most likely explanation for the increased resistance to heat loss in both groups of birds.
- Cockatiels are born nearly naked and pin feathers start to appear at about seven days.
- On that particular afternoon I recall a lot of references to ‘pin feathers’ interspersed with colorful expletives.