A knife, or a blade is sharp.
A needle is…??
It doesn’t sound very good to saw that a needle is sharp.
Pointy isn’t that good either, because when I say “this dagger is sharper than that”, it doesn’t sound the same when i say “this needle is pointier than that.”
So what’s the “sharpness” equvilent for a needle?
Maybe it is more cuspidated?
Pointy. That gets your message across, doesn’t it?
But needles can be blunt. Why not sharp? Or, “careful, friend, there’s a needle over there.” That you use the word “needle” to describe the object in question should be enough to make someone look out. If not, then they deserve to be stuck.
Have you thought about “pointy” or “sharp”? 
Aren’t people reading the post?
Maybe you’re making the Q unanswerable. Pointy, piercing, and sharp seem to do the job for most of us.
Perhaps you should try for sounds of impact. There are lots of those with which the people here can help you.
Sewing needles at least, are sharp:
You can refer to a needle as “fine” to express its thin-ness. The thin-ness, of course, is what allows easier penetration (assuming the needle isn’t so fine that is bends) since the force is delivered to a smaller cross-section.
Precedent is established by coarse, medium and fine penpoints, which are similar in shape to needles; cylindrical and tapered to a point.
Lots of needles are measured by “gauge”, which correponds to the diameter.
Based on the above, I would say this needle has a smaller gauge than that needle.
Gauge is fine, as far as it goes. That denotes the size of the shaft, consequent to how big a hole it will make when inserted into the fabric. If you put a needle under a magnifier, you’d see that it does have blades like a knife. Needles are manufactured for different fabrics, there are special leather and denim needles, which have eyes and scarfs[the channels the thread lies in] of differing sizes. Topstitching and metallic needles to allow thicker or more fragile threads to be used. It has been noted that needles can be blunt, as some are manufactured that way, rather than becoming blunt with use. Ballpoint needles, used for sewing knitted[as oppsed to woven] fabrics have a slightly rounded point so as to pass between the fibres instead of actually piercing them. The integrity of the fibres are maintained this way. The needles are, however, still somewhat sharp. There are needles called “sharps”, for hand and machine use. A needle becomes duller[more blunt] with repeated use, so I suppose the correct term is a new needle is sharp[on it’s way to being dull, after a certain amount of use] Never actually thought about it until I read the OP. Poke yourself with an out-of-the-package needle, and believe me, the first thought that springs to mind is, “Damn, that was sharp!”
**acuate **
“This needle is more acuate than that.”
“needly?”
My vote is with sharper. Needles used in the medical field are hollow. The ‘pointy’ end isn’t really pointy, it’s beveled, if you look at the end under magnification, you will see that it’s sharp, like a knife blade. The only difference is that the blade is circular instead of straight.
A needle is pointed.
That does not imply it is sharp or dull but speaks about the shape itself.
<b>quiltguy</b> mentioned that one would think it was sharp first when pricked. But that adjective is correct only after finding out that the pointed needle is sharp.
Blunt
Pointed
Needle Pointed
Finely pointed
Sharp Point
Very Sharp Point
“Beware of the Cog”
Perhaps you should describe a needles sharpness by the result of an accident or missuse:
Be careful with that needle, it’s a screamer!
or
That needle’s a real yowller.
:rolleyes:
Maybe not.
The needle is keen.
The needle has a fine edge. It is keen.
Same for razors.
Thanks all. I didn’t think of acuate before, and keen is excellent as well.