Lamma Island was named Lamma only because of a chart reading error by Alexander Dalrymple in the 1760s. He had acquired a Portuguese chart to the entrances to the Pearl River and, close to the west of the island, the Portuguese owner had written “Lama”. Dalrymple misinterpreted that as the name of the island. However, it was a Portuguese notation as to the holding (consistency of the seabed from the point of view of anchoring there), which was (and is) mud – in Portuguese “lama”.
In all the early charts the name was spelt with only one “m”. So the island acquired a British name by error and one that subsequently was sinicized by its name being rendered phonetically in characters (“Lama” can mean “south fork” in Cantonese), with the original muddle being all but forgotten. At some point, things became further obscured by the addition of the second “m” in the English spelling. In ancient times, Lamma used to be named as Pok Liu or Pok Liu Chau.