This is the 957th most frequent French word.
régulière
"Régulière" means "regular" or "consistent" in English.
In this sentence, 'régulière' is used as an adjective that qualifies 'routine', suggesting it occurs consistently or in a pattern.
Elle suit une routine régulière chaque matin.
She follows a regular routine every morning.
Here, 'régulière' describes 'participation', indicating that her involvement happens at consistent intervals.
Sa participation au club est régulière.
Her participation in the club is regular.
In this context, 'réguliers' (masculine plural form of 'régulière') describes the sides, implying they are equal in length and symmetrical.