taru-adjective, adverb taking the 'to' particle
slow; lagging; tardy
A literary or formal adverb/adjective describing progress that is very slow or delayed. Often used with として or たる to modify nouns or verbs.
The recovery work is making agonizingly slow progress.
The negotiations made slow progress.
We won't meet the deadline at this sluggish pace.
Though at a painfully slow pace, the economy is heading toward recovery.
緩慢 is a formal word describing a sluggish pace or response in general, while 遅々 is specifically paired with として/たる to describe progress that fails to advance.
遅々 is a literary term for slow progress (esp. in 遅々として進まない), while 牛歩 vividly evokes an ox's crawling pace and is common in political or critical contexts.
着々として進む describes things advancing steadily, the direct opposite of 遅々として進まない, which describes progress that stalls.
遅延 is a concrete noun for a delay (e.g. of a train or schedule), while 遅々 is a literary adjective describing the slowness of ongoing progress, not a single delay event.
long and balmy spring day
Standard kanji form; the repetition mark 々 is used instead of writing 遅 twice.
Non-standard variant without the repetition mark; rarely seen in modern writing.
Reduplication of 遅 (chi, 'slow'), forming a literary adverb/adjective. The exact historical derivation is uncertain, but the form follows classical Chinese-influenced patterns.