Here's how the word evolved:
* "ludere" (Latin): To play
* "alludere" (Latin): To play with, to jest, to refer to indirectly
* "alluder" (Old French): To allude, to refer to
* "allude" (English): To refer to indirectly or casually
The concept of "playing" with language, hinting at something without explicitly stating it, is the core meaning that has been preserved through the centuries.