noun, noun which may take the genitive case particle 'no'
long and uninterrupted; unbroken; continuous
Emphasizes something continuing without a break, often used for abstract things like traditions, efforts, or lines of thought.
この伝統は連綿不断と受け継がれてきた。
This tradition has been passed down unbroken for generations.
連綿不断の努力が実を結んだ。
Continuous effort bore fruit.
A yojijukugo (four-character compound) combining 連綿 (unbroken, continuous) and 不断 (constant, unceasing). The exact historical derivation is uncertain, but the meaning is transparent from its components.