Someone gave me a lilac that they dug up from someones property a few years ago. It's getting larger every year, but it hasn't bloomed at all. I believe a male & female plant is required for blooms, but don't quote me on that! It's not a priority plant for me, so I've failed to do any further research. I always say "one of these days"... Hopefully someone with more knowledge will help us both ;)

No, I don't think you need male and females for lilacs - at least I never heard of it. They just take a little while to bloom and they have to get to a certain size - maybe in the 5' range? My husband and FIL cut down some lilac trees when we moved here - without my permission. They didn't know what it was. Anyway, it took several years for them to bloom again but I don't remember how many.
Plus remember they bloom on old wood so if you prune them, you are pruning the flowers.

Male and female would be for pollination anyway, not for producing flowers.

OK; that's just what I wanted to hear! Mine should be in the 5' range, so hopefully it'll bloom this year, or soon...

We recieved a plant cut from another yard where they were growing tall and flowering well. Two other people also got plants from the same bush. Their plants are flowering and ours are not. My mother did mention to me something about 'male and female'. I have looked this problem up using google and after finding many reasons that a lilac bush may not bloom, we are considering just moving the bush. It is well over 5', growing 'offshoots' and looks very healthy...
Does anyone know what to look for if I were to just buy a new plant that blooms flowers or should is there a way to make the plant grow flowers?