How important is it to understand a word when reading a textbook?

If reading a textbook on heat transfer and there are unfamiliar words, should I stop to understand the words. If i do, will that help me better understand the what the book is saying? Rather than just reading over the word and not having a clue what is being said?How important is it to understand a word when reading a textbook?
Some words are the keys to understanding and you must find out the meaning of the unfamiliar words, that do not take long time anyway with the modern means . I find " Thesaurus on word " extremely helpful and quick.How important is it to understand a word when reading a textbook?
If the word is recurring, better look it up in google to know what all it means. Otherwise, it may not be very significant, though sometimes using the right word is quite important. You may be able to increase your vocabulary. Recently I was enchanted by the correct usage of the two words 'significant" and serious. The scenario was identifying increase in vibration levels.How important is it to understand a word when reading a textbook?
If you do not understand a word, you will not understand or remember what you just read. Skipping words is a terrible habit to pick up.
I think you answered your own question