defail

As verbs the difference between blemish and defail

is that blemish is to spoil the appearance of while defail is (obsolete) to cause to fail.

As a noun blemish

is a small flaw which spoils the appearance of something, a stain, a spot.

As a noun terms

is .

As a verb defail is

(obsolete) to cause to fail.

As verbs the difference between derail and defail

is that derail is to cause to come off the tracks while defail is (obsolete) to cause to fail.

As a noun derail

is a device placed on railway tracks causing a train to derail.

As verbs the difference between detail and defail

is that detail is to explain in detail while defail is to cause to fail.

As a noun detail

is something small enough to escape casual notice.