A 72 mm focal legth lens wont be a 'wide angle' on very much but a large format 1/4 plate camera!
The angle of view of a lens depends on the lens focal length and the size of sensor behind it; my 'medium format' 120 roll film camera, has a 110mm lens that has a 'standard' angle of view, which on a full-frame 35mm film camera would be a mild tele-photol On a small, APS-C sized sensor, that would be even frther into the tle-photo region.
Are you sure you are not confusing the filter-thread diameter, with focal length? And what you have is actually a 72mm filter thread 'lens-adaptor', intended to screw onto the front of your 'kit' lens, like a sort of magnifying glass for your camera, to do 'close ups'?
If so.. it likely wont fit, your 18-140 according to specs I found n Ken-Rockwell's review has a 67mm filter ring.. ie thread o the filter is too big to fit the thread on the lens.... You MIGHT use a 'step-down' adaptor, that would have a 67mm thread to fit the lens one ed, and a 72mm thread to fit the filter the other... but.....
a) on the whole, Filter-Ring lens adapters are, frankly pretty crap! there ISN'T a nice way to say it. It's an extra element on an already compromised lens, it will do nothing to make better pictures than the lens could without it. They are a 'cheap' cop out; an 'effect filter', not a real 'lens' less a propper lens adaptor.
b) Your lens has aprox 18" close focus distance. That is the shortest distance you can get to a subjct and keep t in focus.Fitting the 'macro adapter element'; will likely screw the Auto-Focus system, and it likely just wont focus on anything... you would likely have to switch 'off' auto-focus to actually get a abject sharp in the frame. And its likely that if the adapter filter lets you focus o anything at closer-focus distance, it will be dstorting the image to do it.
c) using a step-down ring to fit 72mm filter to the lens will move the adaptr filter 1/4" further away fro the lens, likely to similarly effect focus, like a spy-glass movng forwards and back between your eye and a book, ad introduce more possible distortion, as 1/4" of the filter adaptor is hanging over the edge of the lens front element.
I acquired a little set of I think three 'macro-filters' in a lucky-bag many years ago; have played with them; they were actually half decent ones as far as I could tell; they are NO substitute for a geune 'macro' lens or a simple reversal ring for your standard lens to turn it back it front on the mount, or f you are absolutely dedicated to the genre, a set of extension rings or 'bellows' rail, which allow close focus and 'may' actually provide genuine on the sensor larger than life 'magnification', without compromising clarity intorducing extra potential distortion from added light transmitting elements i the light-path; and provide meand of actually solving close-focus issues rather than making them!
BUT, all depends on whether what you have is an actual 72mm wide-angle macro lens?!?!? that should fit on the camera in place of your existing lens, or if its a 72mm thread filter adapter that is probably the wrong size to screw onto your lens.
Add on Ed:-
My advicee just stck t n the bin. If you want a wder angle of view, than the 18-140 offers, buy a wder agle lens, but be warned they are damned tricky to get to grips with. If you want macro-close ups; buy a reversal rng or get a macro capable close focus lens.
That s a filter, likely to do nothing but give you wobbly pctures, and make life hard for yourself... and yup.. appears to be a for a 72mm thread filter atatchement, not a 72mm focal length lens. Ie the wrog thread size even for your lens!
Add-on add-edd! marking says 0.45x, implying it offers a 0.45 focal length 'magnification'. Eg, it has the similar effect to reducing set focal length by more than half.... so an 18-140 set at the 18mm wide angle end of the zoom range 'should' have the effectve angle of view of an 8.1mm focal length.....
Err... yeah!!!! That is well down in the range of UWA lenses.... in fact.. have the Sigma 8-16 UWA.. at that short a focal length, even THAT supposedly rectilinear corrected ultra-wide angle is showig some pretty noteable and oft distractng 'fish-eye' distortion, as you are in the sub 10mm range where lenses that short tend to be un-corrected bow front 'fish-eyes'... and it sn't even a fsh-eye adaptor.
It may not be 'so' wobbly on a kit lens at maybe 26mm foal length, where it's magnification ratio would keep the effective focal length over 12mm'ish... but, no... just no... what that is, is a waste of time, it really is.
I really do like wide-angle photography, which is why I ow both a genuine 'full round' 180 deg field of view fish-eye and an 8-16mm UWA; And ca tell you categorically, that even with a dedicated wide or fsh-eye lens, they are damnably difficult to make work for you ad get pleasant results; working with somethng that is, sorry to again be brutally blunt, but as optically useful as a christmas cracker toy, is just NOT gong to help you explore, or enjoy those genres of the pursuit or get anything like pleasant results; and likely put you OFF even trying, as you just wont get pleasant 'results' with one... you really wont. Hard enough with the real deal lens for the job.. and THAT just isn't! orry