Sentence:  More than once I was confronted by professional gamblers , `` bookies '' , loan `` sharks '' , gangsters , `` thugs '' and `` finger men '' - people of a class I did not even <WSD>know</WSD> existed - to repay my husband 's staggering losses , `` or else '' . 
Meaning of the word marked with <WSD> tags:  be cognizant or aware of a fact or a specific piece of information; possess knowledge or information about