What do the Portuguese house terms actually mean?

Most of the confusion in an Algarve house is vocabulary rather than engineering. An esquentador is not a boiler, a termoacumulador is not the same appliance, pladur is a brand name that became the word for plasterboard, and potência contratada is a number you chose once and probably never revisited. Each entry below defines one term in isolation, says why it matters to a repair, and where a figure or a rule is involved, gives the source and the year.