KanjiJLPT N1
Dr.

Dr., command, esteem, win acclaim, Ph.D., exposition, fair

Mnemonic

At the crossroads of every specialty stands a figure who has mastered them all — the one everyone calls Dr. They crossed boundaries between fields, turning each specialty into another feather in their cap.
Additional thoughts
Imagine a grand intersection where all academic disciplines converge. One robed scholar stands dead center, having conquered every specialty. The cross represents the meeting point of all knowledge.
Quick recall
At the crossroads of every specialty stands the Dr.

Details

The keyword for 博 is dr. this kanji carries the meaning of broadness, wide knowledge, and erudition, which is why it became associated with the academic title of doctor. It conveys the idea of being extensively learned or having wide-ranging expertise. In its most common modern usage, it appears in the word for "doctor" (as in a Ph.D. or scholarly doctorate), reflecting someone who has achieved a broad and deep mastery of knowledge.
On'yomi
はく、ばく