having succeeded or being marked by a favorable outcome
"a successful architect"
"a successful business venture"
Resulting in success; assuring, or promoting, success; accomplishing what was proposed; having the desired effect
"The new marketing campaign proved successful by driving a thirty percent increase in sales within the first month."
In plain English: Successful means achieving what you set out to do or reaching your goals.
"The new coffee shop has been very successful since it opened last month."
Usage: Use successful to describe an outcome that achieved its intended goal rather than one that merely produced a positive result. Distinguish it from synonyms like effective, which emphasizes producing a specific reaction regardless of whether the original objective was met.
The word successful is formed by adding the suffix "-ful," meaning full of, to the noun success. It entered English as a straightforward combination that describes someone or something possessing the quality of having succeeded.