Humanoid is a term ubiquitous in both fantasy and science-fiction, meaning "a creature that is similar to a human but not a human". It's a catch-all term for literally any race other than just plain-old humans. Unless you're talking about Dungeons & Dragons, in which it case it has some more specific meanings.
In Advanced Dungeons & Dragons, for unknown reasons (possibly due to his belief in the importance of humanocentrism), Gygax divided the various nonhuman into two categories. Anything that was either half-human or had been a protagonist race in The Lord of the Rings was deemed a Demihuman (why gnomes got in on this, who can say, maybe due to their basically being an elf/dwarf crossbreed). Anything else that had a roughly human-like form and some level of civilization was deemed a Humanoid. On paper, this was a neutral term referring to all non-demihuman races, from benevolent-to-neutral ones like centaurs, firbolgs and aarakocra to evil ones like orcs, ogres, goblinoids, gnolls, kobolds, etc. In practice, it was just used as a catch-all phrase for "all the races you are legally allowed to kill in this game".
When Dungeons & Dragons 3rd Edition came along, they figured this was a clumsily used (and stupid) idea, so they dropped the whole thing. Instead, they divided the various creatures of the D&D multiverse into "creature types", which define the potency of their racial hit die and some default immunities; Humanoid became the "normal type" - the races that were fundamentally human-like in nature, being creatures based on relatively normal biology with little in the way of truly powerful inherent magic. For example, a Medusa is a Monstrous Humanoid, because she can turn you to stone with a look; a Gnoll or Lizardfolk, on the other hand, is just a human-shaped animal, and thusly is a Humanoid type.
This second version has undergone revisions over subsequent editions, but has remained the definitive version, casting the AD&D original into the dank depths of OSR.
In Star Wars humanoid is used to mean a species with two legs, two arms and a head connected to the same torso. Being or scaly is no obstacle to being classified as "humanoid", but additional limbs are. Related to humanoid is the "Near-Human" classification, which is applied to species that are immediate off-shoots of humanity. Only near-humans are known to have produced hybrids with humanity.