Limau is a term used in Malaysia and Indonesia somewhat generically for citrus fruits.
Adjectives are tacked onto it to further clarify what fruit exactly is meant.
- "Limau" by itself is a lemon;
- "Limau Bali" is a pomelo;
- "Limau gedang" is grapefruit;
- "Limau Kesturi" is a Kalamansi Lime;
- "Limau langkat" is a mandarin orange (Citrus suhuiensis), that may have green or orange skin;
- "Limau manis" is a European bitter orange (even though "manis" means sweet);
- "Limau nipis" is a key lime (Citrus aurantifolia Swingle) variety with seeds;
- "Limau Perut" is a kaffir lime leaf (Citrus amblycarpa.)
Whenever you see a recipe calling just for "limau fruits", unless otherwise specified, just use a lemon. If the recipe writer describes it as having dark green coloured skin, then they probably intended "limau nipis", aka key lime.