Considerable means big enough to matter. A considerable sum of money, a considerable delay, considerable damage to the roof — in each case the size is worth taking seriously.
It is a quiet, slightly formal word that lives in reports and in polite understatement: the operation carries considerable risk, he went to considerable trouble. It sits in front of uncountable and abstract nouns — considerable time, considerable effort, considerable skill — and sounds wrong in front of things you count one by one. The adverb considerably does most of the work in comparisons: considerably cheaper, considerably worse, considerably more than we were told. A person can be considerable too, meaning important in their field: a considerable poet, a considerable scholar. Do not mix it with considerate, which means thoughtful about other people; the two words look alike and mean nothing alike.
1adjectiveconsiderableLarge in amount, size or importance.
“The repairs cost a considerable amount of money.”
synonyms: substantial, significant
2adjectiveimportantOf a person: important, and worth respect in their field.
“She was a considerable poet before anyone printed a word of it.”
Too few real examples of this word to estimate which sense is commonest.
Latin
considero
Middle French
considerer
Middle English
consideren
English
consider
English, today
considerable
From consider + -able. consider comes from Middle English consideren, from Middle French considerer, from Latin considero.
Etymology from Wiktionary, CC BY-SA