I noticed that if you search the internet, there isn't a good reference to where the term "FIRE" came from.
Some credit FIRE to the authors of Your Money or Your Life, Joe and Vicki Dominguez. While they did an outstanding job of making the case for a "living below your means" (LBYM) lifestyle, the investment advice in the book (i.e., take a 7% annual withdrawal from a portfolio of US Treasury bonds) was tragically inadequate and would have left you bankrupt over the long term.
Another noteable "retire early" author, Paul Terhorst Cashing in on the American Dream -- Retire at 35 limited his investments to a laddered portfolio of FDIC-insured Certificates of Deposit (CDs) when he quit his Big Eight accounting job in 1984. More recent interviews reveal that he now holds "a more traditional portfolio heavily weighted with low-cost [equity] index funds" today.
In May 1999 the "Retire Early Home Page" discussion board appeared on The Motley Fool website, and a vibrant conversation on early retirement topics ensued. Before The Motley Fool shut the board down in May 2022 (and converted it to "read-only" status) it had accumulated almost 900,000 posts. (The board was renamed "RetireEarlyCampFire" some years after its founding when it was overrun by right-wing political posts.)
One early topic of discussion was the definition of "early retirement" -- and the consensus was that some form of financial independence was a prerequisite. Quiting your job with an insufficient nestegg, and risking an early return to paid employment, was more of a "job change" than early retirement.
By August 2000 a poster with the handle "fzabaly" reduced the long form "financially-independent, retired early" to FI/RE. (post #16089)
Then in January 2001 poster "wanderer0692" made a seminal post "things that are stronger than death and fear" (#29265)
Has anyone else noticed how "FI/RE" looks like the word "fire"? I remember attending church (a long, long time ago) and, during the benediction, the preacher saying, "Take our minds and think through them. Take our eyes and see through them. Take our hearts and set them on fire." I always liked that turn of phrase.
I'm not much for religion, but I do believe in the sanctity of the human spirit. FI/RE is a fire that burns in me. Maybe it consumes me, but I like to think I am that phoenix, rising from the ashes, to fulfill his special mission of realizing his true potential.
So, from now on, I'm gonna drop the slash. A "FIRE" it is. May it be ever thus.
Wanderer, hopefully not sounding too "unhinged"
And that appears to be the first instance of "FIRE" being used to describe an early retirement plan.
Resources for more information
Minimizing the "Skim" -- the Key to Retiring Early - now that I'm 28 years into the "4% rule" and qualified for Medicare at age 65 in 2021, I thought it might be useful to summarize what worked over the past 25+ years.