first out; going first; leading off
Used in contexts like games, competitions, or sequences where someone or something is the first to appear, act, or be presented.
じゃんけんで先出しはグーに決めた。
In rock-paper-scissors, we decided that the first move would be rock.
会議では、新人が先出しで意見を述べた。
At the meeting, the newcomer spoke first and gave their opinion.
Compound of 先 (saki, 'ahead, first') and 出し (dashi, 'putting out'), from the verb 出す (dasu). The exact historical derivation is uncertain, but the meaning is transparent from its components.