Here are some definitions to help models and photographers communicate and understand each other better. Knowing the definitions will minimize misunderstandings.
LINGERIE / SWIMSUIT / BIKINI
Lingerie shoots can be tricky. Models that are not comfortable with nudity are often OK with lingerie and swimwear. It is worth noting that lingerie can be see through or very revealing. Make sure to set your boundaries on your comfort levels and carefully look over lingerie before agreeing to wear it. It is also note worthy that it is perfectly acceptable to change your mind about an outfit upon seeing yourself in it.
Implied nudity is when a model is comfortable being nude, but does not want any erogenous zones to show (no breasts / nipples, crotch showing). It is worth noting that the butt crack is not considered an erogenous zone unless more explicit parts can also be seen.
Some models are comfortable with some nudity but not full nudity. Partial nudity is when either the breast or the crotch area is exposed, but not both. Some models are not comfortable with certain parts of their body being seen. If this applies to you, set those boundaries and expectations in advance.
FULL NUDITY WITH IDENTITY CONCEALED
Some models are comfortable with full nudity, but feel the need to conceal their identity due to a large range of reasons, often due to work, or social reasons. This is an option for those who have concerns.
Full nudity is exactly what is sounds like. The images do not have to be close up, or erotic in nature to contain full nudity. In full nudity nothing is covered and no attempt to conceal the body is made.
Light bondage is where the model is posed restrained or tied up. There are several things to note about this. Light bondage involves simple, easily removed restraints. Light bondage can, but does not automatically involve nudity. PHOTO SHOOTS ARE NOT KINKY BONDAGE SESSIONS. No actual BDSM play should occur without express permission by everyone involved.
Heavy bondage starts to get into more extreme poses. Typically, bondage is considered heavy if the restraints cannot be undone quickly and the models movement is severely restricted. Heavy bondage often involves blind folds or ball gags which restrict the model knowing what is going on, or calling for help. PHOTO SHOOTS ARE NOT KINKY BONDAGE SESSIONS. No actual BDSM play should occur without express permission by everyone involved.
Rope work is popular due to the pretty designs made. Note that rope work does not automatically mean leaving the ground. Models should not leave the ground or be suspended unless they and the person tying them are experienced and agree to leave the ground ahead of time. Rope work does not automatically involve nudity. PHOTO SHOOTS ARE NOT KINKY BONDAGE SESSIONS. No actual BDSM play should occur without express permission by everyone involved.
Suspension is when rope work leads to the model leaving the ground. Rope work can be very dangerous and should only be attempted by experienced people (both the person tying and the model being tied). This involves a lot of good communication ahead of time. Suspension does not automatically involve nudity. PHOTO SHOOTS ARE NOT KINKY BONDAGE SESSIONS. No actual BDSM play should occur without express permission by everyone involved.
Explicit material is any material that is overtly sexual in nature. This often involves sexual acts or penetration. If you plan on doing explicit content, make sure you know what you are agreeing to up front and know where your boundaries lay.
I hope this helps clear things up for both models and photographers and facilitates good communication. Please let me know if there is further clarification needed or if you have feedback on my definitions.