Anthropomorphism

Anthropomorphism is equivalent to giving humanized appearance to objects that are not human directly. Nonhuman objects can be animals, plants, inert beings or whatever (including abstract entities and concepts). Some examples:

Furry
Hybridization with animals:

Pareidolia
See human faces where there really are not:

Gijinka (or moe anthropomorphism)
Instead of following the actual human form, the human form of the manga/anime style (mostly moe style) is followed. In the vast majority of cases, they are usually women (between adults and girls/lolis), forcedly and with a very human physical appearance (they try to make "what they want to represent" to be shown as if it were clothes).

Relation with the GTS community
There are times when non-human objects interact with women, giving rise (in most cases) to pseudo-giantesses: