progressive aspect
A grammatical term referring to the verb form that expresses an ongoing action or state, such as the English 'be -ing' or Japanese ～ている form.
The progressive aspect in English is expressed with 'be + present participle'.
In Japanese, '～ている' often expresses the progressive aspect.
From 進行 (progress) + 相 (aspect), a direct translation of the English grammatical term 'progressive aspect'.