I think it means different things to different people, I think its also expressed differently. I also think that for some people who are dysfunctional, words and gestures do not match irrespective of whether they "think" they love you. Of course most people are not dysfunctional, and in order to feel they are loved have a set of conditions that must be met. Respect, trust, warmth, acceptance, honesty...
I don't so much think the only issue is with the "sender" as with the "receiver" so I think its about how someone makes you feel. Do they make you feel respected, cared for, accepted etc,...or perhaps as is sometimes the case, someone is incapable of being loved, they simply can't accept it.
I could say I love anyone, and I really could believe it to be true, but I can only try to ensure that person "feels" loved by my words and actions. Of course I could be completely dysfunctional, say I love, because I do, and then fail to understand how properly to convey that feeling to the object of my love.
See what happens when you over-think it! and surely if you have to ask the question you don't actually feel loved.