He overcame countless difficulties to succeed.
Countless stars shone in the night sky.
A great deal of research has been conducted on this issue.
Among the countless works out there, this one is the most highly regarded.
数多く is a slightly formal but still common expression meaning 'in large numbers', while あまた is more literary and less frequent.
幾多 and あまた are both literary words for 'many/countless', often interchangeable in formal writing.
多数 is a more neutral, statistical-sounding word for 'a large number', whereas あまた carries a literary, elevated tone.
少ない means 'few, little in number', the direct opposite of あまた's 'many, numerous'.
Applies to each form listed below
Usually written in kana; the kanji forms 数多 and 許多 are rare and literary.
Rare kanji form; the reading あまた is a jukujikun.
Rarely used kanji form; the reading あまた is a jukujikun.
The exact derivation is uncertain; the word has been used in classical Japanese with the meaning 'many'.