Both tags convey the idea of a penis or similarly shaped object just about to penetrate any of the recipient's orifices, but hasn't actually penetrated yet. I went with 'penetration' since it depicts an action that's just about to happen, while 'insertion' would be focusing on the noun.
Thought I'd try and clean the imminent penetration-related tags and tighten up the definitions, plus create an umbrella tag. From what I understand, penetration is treated as a verb while insertion refers to the object/noun on Danbooru, so I went with the insertion -> penetration alias.
I wasn't positive about adding imminent_rape and imminent_sex to the BUR. I'm trying to focus on the act of a penis/object being right in front of the intended penetrating orifice, but not actually penetrating it yet. These two tags don't always qualify as there are other motions/acts that can serve the same purpose.
Yeah, I realized that after making the request. I eliminated the third paragraph from imminent_penetration, and nuked the imminent_sex tags from the request to fit with the current definitions for the *_object insertion tags. Imminent_sex will have to be added manually by the tagger so that images with penises can be isolated from images with objects.
Also had to update imminent_vaginal and imminent_anal to fit with *_object_insertion as well.
(As to OP, "insertion" describes an act as readily as an object.)
I guess so. TBH, I didn't really know whether to go with imminent_penetration or imminent_insertion as the aliased umbrella tag since both words are used rather equally on other tags.