• 巣立すだつ — to leave the nest / become independent
• 巣箱すばこ — birdhouse / nesting box
• 病巣びょうそう — lesion / source of disease
• 古巣ふるす — old nest / former home
• 卵巣らんそう — ovary

The character 巣 suggests a protected home (a bird beneath a roof-like cover), conveying both literal nests and figurative bases or centers.

この鳥とりは 巣すを作つくっています。
This bird is building a nest.

子こどもたちが 巣立すだちました。
The children have flown the nest (become independent).

森もりには 多おおくの巣すがあります。
There are many nests in the forest.