This is the 171st most frequent Romanian word.
doilea
"Doilea" means "second" in English (ordinal number).
The phrase 'capitolul al doilea' uses 'al doilea' as an ordinal number meaning 'second' to describe the position of the chapter.
Am terminat capitolul al doilea din carte.
I finished the second chapter of the book.
The sentence 'al doilea pe listă' uses 'al doilea' as an ordinal number to specify his position on the list.
El este al doilea pe listă.
He is the second on the list.
'A doua zi' employs the feminine form 'a doua' to agree with the feminine noun 'zi', still indicating the ordinal number 'second' in context.