“What does that word mean?” costs you two seconds. Pretending you know it can cost you the whole conversation.

One unknown word is cheap. Guessing at it is expensive, because everything you build on top of the guess is now slightly off, and you will not find out how far off until much later, often in front of people. Asking usually helps the two or three others who did not know either. The embarrassment you are avoiding is smaller than the one you are arranging.

Next time a word goes past you, ask on the spot rather than planning to look it up afterwards. Keep a note of the ones you had to ask about. In a month you will be asking far less often.