halo

Worth being exact about, because English "hall" covers more ground than this word does.

The dictionaries give halo two related senses, and both are large and public. The first is a roofed structure on pillars sheltering a market - a market hall, a covered market. The second is a very big room inside a public building: the concourse of a station, the hall of a castle or a church, the space around an indoor swimming pool. An exhibition hall, ekspozicia halo, is the typical modern use.

What halo does NOT mean is the hallway of your house. That is koridoro or vestiblo. A drawing room or reception room is salono. Both English senses live under one word, so this is a quiet false friend rather than a loud one.

The homonym. Halo! shouted down a telephone is a different word entirely, an interjection borrowed from the same English source that gave us "hello" - some writers spell it haloo to keep the two apart. And the ring of light around the moon, which English also calls a halo, is aŭreolo in Esperanto, not halo.

A false seam, cheaply avoided. There is no root hal- plus a suffix here. Halo is one root of three letters, hal-, plus the noun ending -o. The apposition and affix-like roots article deals with the general problem of short roots that look like something they are not.