The dictionary version (and why it doesn't settle anything)
If you want the textbook line: bisexual means attracted to more than one gender; bi-curious means open to it but not yet certain or not yet experienced. That's the version on every glossary page, including ours — see bi and bi-curious.
What the dictionary won't tell you is that almost nobody uses the words this cleanly. Plenty of men who call themselves bi-curious have done more than they let on. Plenty of men who call themselves bi haven't slept with anyone but their wife.
The words do a job, and the job isn't taxonomy. The dictionary is a starting point, not an answer. Once you know what each word technically points at, the harder question is what work you're asking it to do.
What the words actually do for you (permission vs identity)
For most men, "bi-curious" is a permission word. It says: I'm allowed to think about this, allowed to look, allowed to find out, without committing to anything. It's a holding pattern, and a useful one — making any identity claim before you're sure tends to feel worse than not having a word for it at all.
"Bi" is an identity word. It says: this is part of who I am, regardless of what I do about it on any given Tuesday. It survives long stretches of nothing happening.
It survives changes in your relationship status. It carries on being true when you're not actively thinking about it.
The honest test isn't "which word is correct" but "which word lets me think about this more clearly". For some men that's bi from day one. For others it's bi-curious for years before anything else feels honest.
Why "curious" tends to be a stage, not a destination — but only sometimes
If you stay with the question long enough, "bi-curious" usually moves. Either you discover the curiosity was a phase that passed, or it consolidates into something steadier and the word stops fitting because it's now too small for what you've come to know about yourself.
That's the typical arc — but only the typical one. Some men sit comfortably with bi-curious for a decade or longer because that's a real description of where they live: open, occasionally interested, never quite enough to claim a heavier label. There's no rule that curiosity has to lead anywhere.
What's worth noticing is whether the word is still doing useful work. If "bi-curious" still feels like the truest word for you after years, fine. If you're using it to keep something at arm's length that isn't really at arm's length any more, that's worth knowing too.
Who uses which word, and why
Younger men, broadly, are more comfortable using "bi" early — partly because the word has been less stigmatised in their lifetimes, partly because queer and fluid sit nearby as alternatives. They aren't waiting for 50/50 attraction before using it.
Older men, married men, and men who came up in less open eras tend to reach for "bi-curious" first. It's softer, it doesn't require explaining yourself to anyone, and it leaves the door open without making any claims. If that describes you, coming out later in life covers ground that's specific to that route.
Neither group is more honest than the other. The word is a tool, and different tools fit different hands.
When the label stops being useful
There comes a point — for some men sooner, for some never — where "bi or bi-curious" stops being the interesting question. The label was useful while you were trying to think clearly about which word fitted; once that's settled, it tends to fade into the background. You don't have to officially upgrade from one word to the other when something changes.
The "what do I actually do about this" question is a different one, covered on am I bi? and across the exploring section. This page's job ends at the word.
A note on language changing (and the reader's right to change with it)
The words people use for this have shifted within most readers' lifetimes, and they'll shift again. "Bi-curious" was barely in circulation thirty years ago.
"Queer" has gone from slur to reclamation to umbrella term and is still moving. "Fluid" sits where it sits today and might mean something slightly different in ten years.
You're allowed to change the word you use as you change. The man who called himself bi-curious at twenty-eight isn't lying when he calls himself bi at forty-two. He learned more about himself, and the word he used learned with him.
If you're earlier in this process, am I bi? sits beside this page and addresses the bigger question directly. If you're closer to acting on something, your first time with a man covers the practical side. The label is yours, and so is the timeline.