It seems ironic to be defining the term 'dictionary,' but here we go! Dictionaries are resources for finding word meanings, parts of speech, word origins and even synonyms and antonyms. Dictionaries have definitely evolved over the years. The English language really began with the Anglo-Saxons in Great Britain.
If it is a US Passport, that it is the 9 digit number located in the top corner of the passport info page. In the example below the passport number is 31195855. Other Countries have different types of numbers (usually with letters added) but most often it's in the same place. This Canadian Passport number is AB504966.
For Non-Immigrant Visa, Visa number is the RED Number on the Visa itself. This answer is from USCIS. It is the RED number - check out this CIS Form that advises under Visa # (not the control number that begins with a year) Please refer to the related link for more information. 1  If you mean a non-immigrant visa such as a B1, B2, F1, H1B, then it's on the visa itself. The visa would be the nice-looking laminated sticker (the new ones, at least) on your passport, and the number would be a long number on the top of the visa.