semi-

1. Lethal in more than 50 percent but fewer than 100 percent of cases.
2. A mutation that in the homozygous condition produces more than 50 percent mortality but not complete mortality.

Half-moon shaped; crescentic.

A partial or semicomplete metamorphosis

1. A feather intermediate in type between a contour feather (body feather, as opposed to a wing or tail feather) and down.
2. A feather which has a plume-like web, with the shaft of an ordinary feather.

Not growing or living entirely on land; partly terrestrial.

An interval equal to a half tone in the standard diatonic scale. Also called half step, halftone.