In some large, traditional Filipino families, there is a hierarchic order and manner for how one addresses their older siblings. This actually comes from Chinese/Japanese sources.
For the boys, the first three oldest are usually addressed as kuya, diko and sangko; while the oldest three sisters are ate, ditse and sanse.
The oldest brother is kuya. It’s from the first Chinese ordinal, co. Remember when Charlie Chan referred to his sons as Son No. One and Son No. Two? Well, they indeed came into the world in that order. Present-day Chinese-Filipino surnames which start with “Co-“, like Cojuangco, Coseteng or Cua, for example, all denote having come from the oldest son.
The term for oldest sister, ate, comes from aitche (“ichi” meaning “first” in both Japanese and Hokkien, one of the Chinese dialects).
Diko, brother No. 2, and ditse, second sister, are rooted in “di” (or ni or ji, depending on your regional Chinese or Japanese bent). Just so long as it’s not “ditzy” as might be concocted by a mischievous first-born.
Child No. 3, sangko and sanse, come from the Japanese sansei, i.e, third in line.
In reverse order, the youngest one is lovingly called the bunsó, neutral-gender. To be gender-specific, totoy (the literal translation from Chinese is “the foolish one”), atoy, toto, itoy, doy are variant names given the youngest boy. The youngest girl was often called nene (literally, the “dull one” in Chinese.