【Elastic】 ,  【expansive】 ,  【resilient】 ,  【buoyant】 ,  【volatile】 ,  【effervescent】  are comparable when describing persons, their temperaments, moods, acts, or words and meaning indicative of or characterized by ease or readiness in the stimulation of spirit and especially of high spirits.

【Elastic】 implies an incapacity for being kept down in spirits; specifically it may suggest an ability to recover quickly from a state of depression or a tendency to moods of exaltation, elation, or optimism.

【Expansive】 implies exaltation of spirit that tends to make a person unusually genial, communicative, or sociable.

【Resilient】 usually implies a return to normal good spirits, which may or may not be high spirits.

【Buoyant】 implies such lightness or vivacity of heart or spirits as is either incapable of depression or that readily shakes it off.

【Volatile】 implies diametrical opposition to all that is serious, sedate, or settled; it therefore suggests lightness, levity, or excessive buoyancy of spirits and often flightiness or instability.

【Effervescent】  implies liveliness, often boisterousness of spirits; it often suggests the effect of release after restraint and even more than  【buoyant】 implies the impossibility of suppression so long as the mood or temper lasts.