From Polish Foruns : (http://www.polishforums.com/language/jeszcze-wciaz-44481/)
jeszcze - YET (used with negative verbs) Nie zrobiłem jeszcze zadania domowego. – I haven't done my homework yet.
wciąż - STILL (up to a time, as in the preceding time)
The word "wciąż" implies "persevere" whereas "jeszcze" implies only "still". And so, by using "wciąż" you mean that you still (for example) "work there" and yet you are not endangared but at the same time you are not peculiarly happy about working there. If I used "jeszcze", I would mean that I am "working there" but I may (or may not) be on my way out, voluntarily or not.
1) most online translators are bad when it comes to the Slavic languages, because they're based on English-like grammar; 2) it would only be translated to "constantly" from a very, very specific context; 3) a lot of English words don't have their exact Polish equivalents, and a lot of Polish words don't have their exact English equivalent - which means that the best way to translate is to approximate the meaning; so, the online translators provide so many words as the possible translations in order to cover as many meanings of the word as possible - but the online translators can't reliably choose which of those words fits the best in a particular case, because they do not recognize context.