The word 'undammed' is a modern English formation built upon the core noun and verb 'dam,' which traces back to Middle English 'dam,' likely from a Germanic root related to blocking or confining water. The prefix 'un-', of ancient Germanic lineage, is systematically applied to reverse the state, creating the meaning "not having been dammed." The adjectival suffix '-ed' completes the word, indicating a resultant condition. Thus, the literal construction "not-barriered" evolved from a concrete description of waterways to also encompass metaphorical senses of emotional or creative expression flowing without restraint.

Structure: un (not) + dam (barrier) + med (adjective suffix) - un: A prefix of Germanic origin (Old English) meaning "not," used to form negatives. - dam: A morpheme from Middle English, referring to a barrier to obstruct water flow. - med: A variant of the past participle suffix "-ed," used here to form an adjective meaning "having been subjected to the action of the verb."