The Chinese had two words for tea; 荼 (tú) and 茶 (chá). In Europe "tú" eventually became "tea" in English, "thé" in French, "tee" in German, and so forth. But in most of the rest of the world "chá" was used as the root for "Chai". Interestingly "trà" is tea in Vietnamese, which seems to be a combination of both.
So as you can see, chai simply means tea. However, when English speakers say "chai" they are most certainly referring to "masala chai", which means "spiced tea" and is a common drink in India.
The spices used can be almost anything, but in general they include ginger, cinnamon, cardamom, clove, and black pepper. (These are the ingredients we use in our blend.) These spices are combined with Assam CTC black tea and added to simmering milk with honey or sugar. The mixture is then strained before serving.