What word that one thumb up is a universal meaning all well?

There isn't one single word that perfectly captures the universal meaning of a thumbs up. However, depending on the context, you could use:

* Agreement: This is the most common interpretation, signifying "yes," "okay," "I understand," or "I agree."

* Approval: This emphasizes the positive sentiment, implying "good," "I like it," or "I appreciate it."

* Support: This focuses on encouragement or solidarity, meaning "I'm with you," "I'm behind you," or "I believe in you."

* Positive: This is a general term indicating a favorable response, "This is good," or "This is fine."

* Good: This is a simple and direct way to convey a positive sentiment.

Ultimately, the specific meaning of a thumbs up depends on the situation and the people involved. It's always best to consider the context to determine the most accurate word.