The word's journey begins with the Latin scrupulus, a diminutive of scrupus, meaning a sharp stone or pebble. This concrete term evolved to signify a metaphorical "small weight" or "anxiety," akin to the nagging discomfort of having a stone in one's shoe. By the 16th century, this sense had crystallized into the modern meaning of a moral hesitation or conscientious objection. The prefix un-, of Old English origin, is then applied to negate this quality, forming "unscrupulous" in the early 19th century to describe someone entirely free from such ethical hesitations or restraints, thereby acting without principle.

Structure: un (not) + scrupulous (having moral principles) - un: A prefix of Germanic origin, widely used in English to express negation or the opposite of a quality. Its functional role is a negative particle. - scrupulous: An adjective from Latin scrupulosus, meaning "full of scruples," from scrupulus, a small sharp stone or a unit of weight, which figuratively came to mean a source of anxiety or a moral qualm. Its functional role is the core adjective describing a person of strict moral integrity.