taru-adjective, adverb taking the 'to' particle
slight; insignificant; trifling
Literary or formal adjective/adverb describing something extremely small or negligible. Most often used in the fixed pattern 微々たる + noun, or adverbially as 微々として.
See also: 微々たるもの
His contribution was insignificant.
This year's pay raise was a negligible amount.
It's not something to worry about in the slightest.
The medicine's effect amounted to only slight progress.
多大 describes something as great or substantial in amount, the opposite of 微々, which describes something as negligibly small.
Standard kanji spelling; the repetition mark 々 is typical for this reduplicated form.
Alternate spelling without the repetition mark; less common but still seen.
Reduplication of 微 (び, 'tiny, subtle'), forming an emphatic literary expression meaning 'very slight'. The exact historical derivation is uncertain, but the pattern is typical of Sino-Japanese reduplicative adverbs/adjectives.