head-in-the-sand

The phrase is a metaphorical idiom originating from the popular but erroneous belief that ostriches bury their heads in the sand when frightened, thinking they will not be seen. This notion was recorded in natural history writings by the Roman scholar Pliny the Elder and became entrenched in Western folklore. The literal image of an "ostrich with its head in the sand" was first used figuratively in English by the mid-19th century to describe willful ignorance or avoidance. By the early 20th century, it had solidified into the hyphenated adjectival compound "head-in-the-sand," succinctly characterizing a person who deliberately ignores obvious problems or facts.

This is a fixed compound phrase functioning as a single lexical unit. It is not productively segmented into smaller morphemes for analysis. The phrase is a metaphorical idiom derived from English vocabulary.