Λυχνία isn't quite that common in Greek. In fact, it's not common at all, and it's used in really specific cases, like λυχνία αυτοκινήτου, or ηλεκτρική λυχνία. You might see it in some Physics books too, but that's it. So you do understand that the originally added translations didn't include such specific terms, but simpler ones, that could be used a bit more often. (like λάμπα, or φωτιστικό). It's been added though. Thanks for the input. ^.^
Και ποια είναι η διαφορά μεταξύ "λάμπα" και "φωτιστικό";
Λάμπα is a lamp, meaning either the actual bulb or the whole device with the decorative bit. Φωτιστικό only refers to the whole thing - with or without the bulb. I often like to check such terms by running a google images search to see how the words are used, it can be illuminating! :D It's pretty clear in this case. Try λάμπα, then φωτιστικό, then λάμπα γραφείου and you'll see the meaning overlap.