Hi
Sometimes I meet English words for which my dictionary refuses to give their stem.
My latest case/example: wistful
wist-ful, OK.
But there is no any wist in dictionaries… and nothing even ‘close to’, with similar meaning…
Another example: tweening / tweened (this is a technique of animation, by creating intermediate frames - between two ‘key’ ones)
I know tween (a noun), but, despite there is no such verb as ‘to tween’, both gerund and Past Participle legally exist.
Tamara
Hi Tamara
Have a look here for a bit of information about wistful:
etymonline.com/index.php?term=wistful
And on the same website, tween:
etymonline.com/index.php?sea … hmode=none
The word tweening is a “specialist” word created by animators. Have a look at the two links:
onlinedictionary.datasegment.com/word/tweening
webopedia.com/TERM/T/tweening.html
I’d say this is pretty similar to all the PC and internet related words that have recently come into English. 
Amy
I studied animation in art school before there were any computers to do it on. The word tweening, as it says on one of the sites Amy pointed you to, comes from a larger compound in-betweening. It means to draw the intermediate steps between two points in the movement of a cartoon.
In the days when cell animation (i.e., animation drawn on celluloid sheets) was all done by hand, there were several jobs in an animation studio:
The animator decided on the general movement of the characters and objects in the film. If a character moved from point A to point B, the animator would draw those two images on paper. Then the in-betweener would draw the steps in between point A and point B (if it’s full animation, and the movement lasts a second, that’s 24 images per second). After those images are drawn, the inker takes over tracing the images onto the celluloid sheets that will be filmed, and then the painter adds the color.
In-betweening is sort of a strange-sounding compound, even to English ears, so I think it’s natural that it got shortened to tweening. This probably happened before desktop computers ever existed.
Hi
Thank you! I didn’t actually think about the shortening…
Yes, by now motion tweening and shape tweening are, perhaps, the two most widely-used software animation techniques. Especially, the first, if you (would) use animation software like Macromedia Flash.
In fact, after you chose the number of tween’s frame range – between two keyframes - you should also set a positive or negative number as a value of Easing parameter (of so-called “easing equation”) to control acceleration (the speed of the flash movement from A point to B point) – and the software will calculate tween’s frames automatically.
OK.
Thank you again for the short - but very interesting for me - English tour!
Tamara
Just imagine that in the old days people had to calculate all that themselves! Those in-betweeners were very highly skilled people! In today’s animation programs, you can do things in minutes that used to take skilled animators days!
There’s another technique from the old days that the software makes much easier, and that is rotoscoping. That means taking a film of live action, usually a person moving, and then doing the animation by showing the film frame by frame through a light box and then tracing the image on each frame onto paper. This is how Snow White’s movement was done in the Disney film.
When I was in school, computer animators had just learned only two years before to shade and smooth the surfaces of the objects they created. Before that, everything had triangular facets, like a diamond. Someone had to work out the math that would make the surfaces look smooth. He wrote his PhD dissertation on it, but only two years later it seemed so obvious, and no one would have thought of doing things any other way.
Computer characters are still animated by dividing them into many triangular facets, which are then smoothed. Now, however, they can do unbelievable things. At one advertising agency I worked at, they videoed the face of an opera singer performing a piece from The Marriage of Figaro, and they divided her face into triangles. Then they divided the face of a baby into equivalent triangles and transferred the movement of the triangular coordinates from the opera singer to the baby. The result was that it looked like the baby was singing opera.
Hi Jamie
Yes, ‘Snow White…’ is the best (and first) example of perfectly coordinated - in tiny details - and manually created tween’s frames for human movement.
I was told that there were about a million (!) of (different kind of) drawings made for the cartoon.
And yes again, you’re right: some ‘break-through’ versions of science-intensive and high-tech software (and other devices and tools) can make ‘meaningless’ – at once! – lots and lots of manual skills and skilful people…
Commemorate slide-rule… 
my Granddad tried to teach me how to use it
And I also remember such a useful thing (at my school time) as so-called Bradis tables…