poluso

Poluso covers the same ground as English pole in its geographical and physical senses, and only those. It is either of the two points where an axis meets the surface of a sphere, hence la norda poluso and la suda poluso; it is either terminal of a battery or a magnet; and figuratively it is either extreme of a spectrum of opinion, which is where polusiĝo, polarisation, comes from.

The false seam. -us is the conditional ending, one of the first things Rule 6 teaches, and by rank 2384 your eye has read thousands of verbs in it. Poluso is not polu- in the conditional. There is no verb polui, the -us here belongs to the Latin polus, and the giveaway is the final -o sitting after it: a conditional verb ends in -us and stops there.

Two neighbours it is not. A pole in the sense of a long stick is stango, a different word entirely and one this course reaches at rank 2468 - a flagpole is flagstango, never a flagpoluso. And a Pole, a person from Poland, is polo, one letter and a whole meaning away. Zamenhof, who grew up in Białystok in the Russian Empire, would have had reason to keep those two apart.