word-choice
If, for example, one girl exploits her appearance to cheat around some males and I want to say that she is "smart" in a "bad" way can I say she is shrewd?
Which one of this words fits more this kind of "smart" people?
What's the difference between that words? (my dictionary see them as synonyms)
What about the concise, memorable, and conveniently alliterative expression WHILE YOU WAIT, which is sometimes seen on business signs?
If someone can remember that three-word phrase (and the pictures I've added might help someone do just that), then it might be easier for them to remember how while would be the word that means "during some time interval."
Once you get one half of a confusing pair straight in your mind, the other half pretty much falls into place by default. But if you wanted something more, you could simply imagine the business owner saying:
I can fix this while you wait; you won't pay until I'm done.
The word former refers to state. It means that the person or object was something, but no longer is. The word "former" only refers to sequence in special cases where it is contrasted with the word "latter" (in which it means the first of two given items).
The word previous refers to sequence. It means that the person or object was/did something before something else took over or replaced it. As StoneyB rightly clarifies in his comment, "the previous" means the directly preceding member in a series, however "a previous" can refer to any earlier member in the series.
The word last, in this context, means the same as "previous", but is only used to refer to the immediately preceding item. (Jay warns that "last" can be ambiguous as it is also used to refer to the final entry in a series.)
Thus, you can say "former coworker" of someone who is no longer a coworker. However, the word "previous" means the one before the current, so saying "previous coworker" or "last coworker" does not make sense unless you had a coworker and they were replaced.
Referring to TV series, you can say that you preferred the "previous" or "last" show, and this would refer to the show immediately preceding the current show. You cannot say the "former" show in this context.
When referring to a show that aired earlier than the immediate previous, you can say "a previous show". Otherwise, you can be more specific. Depending on the circumstances, you might say "the first show", or "one of the earlier shows", or "episode ten", or simply "one of the older shows". You could even say something like "five episodes earlier".
Best Answer
"Shrewd" is not necessarily negative - to call a businessman shrewd is generally a compliment, meaning "taking advantage of hidden opportunities". "Cunning" is more negative, meaning "good at deceiving people" (though in the past it used to be equivalent to "cute"!). "Sly" is about the same as "cunning". You might also consider "scheming" if she has specific intentions, and "devious" if she hides her true intentions.