The word 'tosser' is a straightforward agent noun formation from the verb 'toss', which emerged in English during the early 16th century. The verb's origins are obscure but likely stem from a Scandinavian root implying a light, quick, or careless motion, such as throwing or scattering. By adding the agent suffix '-er', common in English for denoting a person associated with an action (like 'writer' or 'driver'), 'tosser' literally means 'one who tosses'. The transition to its modern British slang meaning as a term of abuse is a semantic pejoration, where the literal act of throwing was metaphorically associated with worthlessness or contemptible behavior, likely influenced by coarse anatomical references.

Structure: toss (throw) + er (agent suffix) toss: Origin uncertain, possibly from a Scandinavian source (e.g., Old Norse tossa 'to tear apart'). Functional role: verbal root meaning to throw lightly or fling. er: From Old English -ere, from Proto-Germanic -ārijaz, a suffix borrowed from Latin -ārius. Functional role: agent noun suffix, denoting a person who performs the action of the verb.