Code Whale
Noun · Slang & Abbreviations
Definitions
A very large or significant technical target, problem, or account that dominates attention. In engineering slang, code whales are hard to land and easy to organize whole planning cycles around.
In plain English: A very large important technical target or problem.
Example: "The legacy permissions overhaul was the code whale of the quarter, big enough that everyone kept referencing it while still finding ways to postpone touching it."