na-adjective, noun
Literary word describing books, documents, or collections that are physically thick or contain a vast amount of content. Often used in formal or written contexts.
彼の書斎には浩瀚な百科事典が並んでいる。
His study is lined with voluminous encyclopedias.
この浩瀚な資料集は研究者にとって貴重だ。
This extensive collection of materials is valuable for researchers.
The word is composed of the kanji 浩 (vast, wide) and 瀚 (wide, vast), both suggesting great extent. It is a Sino-Japanese compound (kango) used in literary contexts.