first in; putting in first
Used when something is placed, inserted, or added before other items, often in contexts like loading, filling, or queuing.
Please put the detergent in the washing machine first, then add the clothes.
This machine requires the materials to be loaded first.
Compound of 先 (saki, 'before, ahead') and 入れ (ire, 'putting in'), literally 'putting in first'.