noun
honeymoon trip
A trip taken by a newly married couple. Synonymous with 新婚旅行, which is more common in modern Japanese.
See also: 新婚旅行
二人は蜜月旅行でハワイに行った。
The two of them went to Hawaii for their honeymoon trip.
More common and modern term for 'honeymoon trip'. 蜜月旅行 is a less frequent synonym.
Compound of 蜜月 (honeymoon) and 旅行 (travel). The exact derivation is uncertain, but it is a straightforward combination of the two words.