Terminology: Is there a technical term for the paired wheels on tricycles? Are there standard technical terms for the location of the wheels on tricycles? I was writing up an answer to another question and was using clumsy terms such as front-wheel on a delta and rear wheel on a tadpole for the singleton wheel that isn't part of a pair. I assume we could just call the singleton the drive-wheel or steering wheel, depending on the configuration although that doesn't always work.

I'm particularly interested if there is a configuration-neutral term for the wheels that are paired (front wheels on a tadpole; rear wheels on a delta). They are what make tricycles unique in being located side-to-side of the rider and they are unique in having single-sided hubs, etc. Are they collectively called the paired wheels, side wheels, or something else? Or is there no agreement and we have to specify the configuration (tadpole/delta) and location (front/rear) each time?
I have been in the recumbent business for over 10 years and have not ever heard a technical term to distinguish the pair of wheels versus the single wheel. As there is so little standardization it would be difficult to describe the wheels without ever running into someone misunderstanding. I used to manufacture front wheel drive two wheeled recumbents and already got into problems since 'my' front wheels were really rear wheels (135mm hub spacing) and 'my' rear wheels were actually front wheels (100mm hub spacing). Then I started to experiment with trikes where I used a delta setup with a single powered wheel on the front (still 'my' front wheel that was still actually a rear wheel) and two single-sided hub wheels. 

Whenever I had wheels made I found it best to describe as much detail as possible (and still sometimes got reversed quantities) and I did the same in my shop.