The word 'spitter' is a transparent English agent noun formed by combining the verb 'spit' with the productive agentive suffix '-er'. The verb 'spit' itself is of ancient, likely onomatopoeic origin, imitating the sound of expelling something from the mouth, and can be traced back to Proto-Germanic. The suffix '-er' has a robust lineage from Proto-Germanic -ārijaz, borrowed from Latin -ārius, and serves to denote one who performs an action. Thus, the literal construction "one who spits" directly and logically yields the modern meaning, whether applied to a person, an animal like a llama, or figuratively to objects that forcefully eject substances.

Structure: spit (to eject saliva) + er (agent suffix) spit: From Old English spittan, of imitative origin, meaning to eject saliva or other matter from the mouth. It functions as the core verb root. er: From Old English -ere, an agent-noun suffix indicating a person or thing that performs the action of the verb.