the adjective 'unworried' is a modern english formation built upon the well-established pattern of negation using the prefix 'un-'. this prefix descends from the proto-germanic un-, which is cognate with latin in- and greek a(n)-, all serving to express negation. attached to the past participle 'worried', from the verb 'worry', the compound directly and transparently conveys the state of being "not anxious." the core verb 'worry' underwent a significant semantic shift from its old english meaning of physical strangulation to the modern sense of mental harassment, making 'unworried' a logical and readily understandable antonym describing freedom from such mental distress.

Structure: un (not) + worried (anxious) - un: a prefix of germanic origin (old english un-), meaning "not," used to form negatives of adjectives and participles. - worried: an adjective of english origin, derived from the verb 'worry', which itself comes from old english wyrgan meaning "to strangle." its modern sense evolved to mean "to cause mental distress or anxiety."