A link like this shouldn't harm your site, and if it is a follow link, could be helping you in the rankings.
Google does not expect every single link to a site to be perfectly relevant and authoritative. There are bound to be a number of irrelevant links to any site, because anyone on the internet can post anything at any time. This site in particular seems to be a high quality, useful site, and even though a dictionary is not relevant to your business, the language you are using on your site IS relevant to text translation.
Unless you are getting many (read: hundreds or thousands) of links from this site, it should have a negligible or slightly beneficial effect on your rankings.