This whole issue on the use of the term 'frame' is ludicrous and annoying.
Let's say I make a video this way.
I prepare a series of 704x480 pixel pictures which represent different instants of time separated 1/59.94 of a second from each other. I offset every other frame by 1 pixel and downscale all vertically (to 240 pixels). I put the result of this process together into a video file,
without interlacing.
I think that noone will contend that it is perfectly correct to say that I have a 59.94 frames/s video. I'll call this video "video X".
Now I take the frames of this video and organize them like this: I take packs of two frames and construct one frame out of them, by taking one horizontal line from the first frame, then one horizontal line from the second frame, then one from the first frame again, then one from the second frame, etc. obtaining in each process an image of 704x480. I put all the images generated by this method together in a video file with a 29.97 frames/s frame rate.
The video generated this way has the characteristics of an interlaced NTSC video, with respect to frame organization and rate. As such, every frame has two fields; the frame rate is 29.97 frames/s or 59.94 fields/s.
Now I take every frame from this video and separate each image into two, by taking every even row of pixels into one image and every odd row into another. I organize the resulting images into a video with 59.94 images per second. If done correctly and losslessly, the resulting video can be
byte-by-byte identical to video X.
So, who is to say that the pictures contained in this last video can't be called "frames" just as they could be called "frames" in video X itself, if both are identical? Does the knowledge that it was once part of an interlaced video make any difference?
As femr2 put it,
A field is only a field whilst it is part of an interlaced frame. Once it is separated from the frame, call it whatever you please...field, frame, image, picture. Context depends upon when you refer to the image, and your prior knowledge of it's original container.
Now it's true that the interlacing/deinterlacing process can introduce changes that need to be accounted for, but that's a separate discussion from this stupid frame/field semantic discussion nonsense. The sampling rate for the data is still 59.94 samples per second, whether they are called samples, images, pictures, frames, fields or whatever.
I should have been more clear that I was referring to typical North American parlance as it relates to 2001 vintage North American footage.