noun
double balloon; bulb with reservoir
Technical term for a bulb or balloon with two connected chambers, used in laboratory equipment, medical devices, or similar apparatus.
実験では二連球を使って試薬を吸引した。
In the experiment, we used a double balloon to aspirate the reagent.
Compound of 二 (two), 連 (connect), and 球 (ball/sphere). The exact historical derivation is uncertain; the term likely arose in technical contexts to describe a bulb with two connected chambers.