Betaori
Betaori (ベタ降り) is a general strategy emphasizing the discarding of safe tiles. By employing betaori, a player has abandoned all hope of developing a completed hand; and instead, the player opts to minimally lose points via opponent tsumo or ryuukyoku. Of course, a player using betaori hopes to not lose points at all.
Genbutsu
Genbutsu (現物) is a term for "safe tile".