This is the 3688th most frequent Japanese word.
いちばん
"いちばん" means "number one," "the best," or "the most."
Usage of 'いちばん' here denotes the superlative degree, indicating 'the tallest' or 'the most high' among all mountains.
私はいちばん高い山に登りたいです。
I want to climb the tallest mountain.
'いちばん' here signifies the quality of being the fastest, showing a comparison among others.
彼がいちばん速く走ることができます。
He can run the fastest.
The term 'いちばん' denotes an individual's preference among various options, indicating 'the most liked' one.