This is the 2029th most frequent Japanese word.
プレ
"プレ" (pure) means "pre-" or "before," often used as a prefix.
Here, 'プレ' is the prefix of 'プレゼント' (purezento), which means 'present' in English. It indicates something intended to be given as a gift.
プレゼントを買いました。
I bought a present.
In this sentence, 'プレ' acts as a prefix meaning 'pre-', indicating something happening before the main event.
プレイベントが行われます。
A pre-event will be held.
Here, 'プレ' is used as a prefix meaning 'pre-', implying preliminary research activities conducted before the main research.