online dictionaries

slovnik.seznam.cz a Czech - English and English - Czech dictionary (one thing to be careful about: often the first word in the list is not what you need)

www.rewin.cz/WebForm1.aspx a Czech - English and English - Czech dictionary

www.online-slovnik.cz a Czech - English and English - Czech dictionary with pronunciation

https://dictionary.cambridge.org an English - English dictionary with easy-to-understand explanations (tip: if you don't understand a word on the website, except for the advertisements, double-click on it and you will get the explanation!)

www.thefreedictionary.com a cool website with a huge English - English dictionary with pronunciation, etymology remarks, thesaurus and encyclopedia, a word and quotation of the day, a few intriguing vocabulary games and interesting articles

[intriguing = challenging, interesting because of being unusual]

[double-click = press a computer mouse button twice quickly]