The word "under-written" refers to financial transactions or investments that have not been fully subscribed or funded. The antonyms for this term are 'fully funded', 'oversubscribed', and 'fully subscribed'. When a financial investment is fully funded, it means that all the capital required has been raised, and the investment can reach its full potential. On the other hand, an oversubscribed investment implies that demand for the investment is greater than the available supply, and not everyone who wished to invest can do so. Both fully subscribed and oversubscribed investments are considered to be successful and in high demand.