Questions & Answers about Η ιατρική αλλάζει γρήγορα.
Here it functions as a noun: medicine or medical science.
Historically, ιατρική is also the feminine form of the adjective ιατρικός (medical), but Greek often uses adjectives as nouns when the meaning is clear. So η ιατρική means medicine as a field.
Because Greek uses the definite article much more often than English.
In this sentence, η is the feminine singular nominative article, and η ιατρική is the normal way to say medicine as a subject or field of study. Greek commonly does this with abstract nouns and academic disciplines.
So even though English says just medicine, Greek naturally says the medicine in form: η ιατρική.
It is feminine singular nominative.
- η = feminine singular nominative definite article
- ιατρική = feminine singular nominative form
It is in the nominative because it is the subject of the sentence: the thing that is changing.