Here are some possible interpretations of what you might be asking:
1. In the context of trade:
* Tariff refers to a tax imposed by a government on goods imported from other countries. This is the most common usage of the word.
2. In other contexts:
* Tariff can also refer to a price list, especially for services. For example, a phone company might have a "tariff" that lists the prices of different calling plans.
Therefore, the full form of "tariff" is simply "tariff". It's a word that has its own meaning and doesn't require expansion.