the past; old times; bygone days
A somewhat literary noun referring to former times or days gone by. Often used in reflective or historical contexts.
往時をしのんで、古い写真を見返した。
I looked back at old photos, reminiscing about the past.
この町は往時の面影をほとんど残していない。
This town retains almost no traces of its former days.
往時 and 往年 are close synonyms meaning 'bygone days', but 往時 tends to describe a past situation or era while 往年 is often paired with people or their achievements (往年の名選手).
Compound of 往 (going, past) and 時 (time). The exact historical derivation is uncertain, but the kanji combination naturally conveys 'times gone by'.