There are a few different functions or features coincident with the concept you wish to terminologically identify
- stud insulation
- sleeving aka boot
- strain relief
- permanently set, aka premolded (and therefore not a boot)
Each of these functions can be had independent of the other. For example, you can have a strain relief elbow which is not a terminal. You could also have a strain relief elbow which is also a termination. There frequently are straight strain relief sleeves about a foot away from the terminal end of USB cables. I guess that is where cables usually get tangled and mangled up.
You could have a termination that is not qualified for strain relief. In which case, you should not contractually tell your client that it is a strain-relieved terminal end.
In many cases, terminal ends are manually crimped as the "cable guy" requires the flexibility of non-predetermined cable lengths before cutting the cable and crimping on the termination sleeve. In such case, the wire or cable termination is usually commercially advertised as terminal sleeves. If strain relief is required, then strain-relieved terminal sleeves/boots. Where the terminal sleeve is appended with the stud appropriate to the occasion.
- termination stud insulation
- termination stud insulation sleeve
- termination stud insulation sleeve with strain relief
- premolded termination stud insulation with strain relief
- premolded insulated termination elbow stud with angular strain relief
Reinvent the wheel
If you might seek to reinvent a term for it especially if you are involved in an entrepreneurial venture to produce such structures, you could use the term
varices, from which is derived the term for medical conditions of varicose veins or arteries. Variac might be a good brand name.
Varix = a swollen section because it is identifiably different (vary) from the rest.
- premolded termination varix/varices.