こそ

1. 1it is ... that ... ; precisely ; in particular ; definitely ; for sure ; only (when, after, because, etc.) Translated by Jiyomi
2. 2although ; while ; it is the case that ... but
3. 3it is precisely because ... that ... ; only because ...
4. 4not at all ; not in the slightest ; absolutely not ; never

JMdict entry 1004410 · frequency rank 50. Source and licence.