What does "fL" stand for on a family tree?

Question:

What does "fL" stand for on a family tree?

I have inherited a genealogical tree of my family which was greated by a British genealogist. Most of the names are followed by "b" which I can interpret as meaning "born" (b. 1784) and some also have "d" which must be the date of death. But many have "fL" (fL 1871). This only seems to occur when there is no date of death. Can anyone tell me what "fL" stands for?

Best Answer - Chosen by Asker: In the nearly 30 years I've done genealogical research, I've never seen this term. But I've found what it means! It is Latin, and means . fl. floruit - was alive at a certain date (fl 1991 = was alive in 1991)

Thanks for helping me to learn a new term!