tankkeissa
Tankkeissa is a Finnish term that means “in the tanks.” It is the inessive plural form of the noun tankki, which can refer to a container for liquids or gases (such as a fuel tank or storage tank) as well as to a military armored vehicle, commonly called a tank in English.
Tankkeissa is used when describing the location of something inside more than one tank. For example, polttoaineet
In Finnish, the inessive case marks location inside something. For words ending in -ki, the plural inessive
Related terms include tankki (singular), tankit (nominative plural, “tanks” as containers or vehicles), and tankkien (genitive
Tankki, tankkit, inessive case in Finnish, Finnish noun inflection.