impulso

This one really is related to pulso, and you may say so. Most of the lookalikes in this chapter are accidents: pulvo and polvo, vizo and vidi, kreto and konkreta. Not this pair. Pulso at rank 2,572 is the beat in an artery, and it is the same Latin pellere as impulso - the pulse is the blood being driven, the impulse is the mind being shoved. Both nouns come from the participle pulsus. The relation is real, it is worth knowing, and it still gives you no Esperanto seam: impuls- and puls- are two separate roots on the list, and im- is not a prefix in this language.

Three senses, one shape. The everyday one is the sudden inner push: pro impulso, laŭ la unua impulso, impulsa homo for someone who acts without stopping. The figurative one is momentum given to a project or a cause: doni impulson al la movado, which is standard in Esperanto organisational prose. The technical one is physics and electronics: an impulso is a pulse of current or a quantity of momentum. Context sorts them out without effort.

The company it keeps. Subita is the adjective that most often sits beside it, instinkto is what an impulse feels like from the inside, and emocio is the weather it arrives in. The verb is impulsi, to give an impulse to, and impulsiĝema is a nicely built word for somebody who acts on every one of them.