taru-adjective, adverb taking the 'to' particle
full of vitality; vivacious; energetic
Describes a lively, energetic state or manner, often used in literary or formal contexts. Functions as a taru-adjective or adverb with と.
Her vivacious smile was impressive.
The children are playing around full of energy.
活発 is a more common and neutral word for 'lively' or 'active', while 生気溌剌 is a literary four-character compound emphasizing overflowing vitality.
元気 is the everyday word for 'energetic' or 'healthy', whereas 生気溌剌 is more formal and vivid.
A four-character compound combining 生気 (vitality, life force) and 溌剌 (lively, vigorous). The exact historical derivation is uncertain, but it is used as a set phrase in literary Japanese.