a holiday spent together by a newly married couple:they flew to the West Indies on honeymoon
[often as modifier] an initial period of enthusiasm or goodwill, typically at the start of a new job:the new President’s honeymoon period
[no object, with adverbial of place]
spend a honeymoon:they are honeymooning in the south of France
mid 16th century (originally denoting the period of time following a wedding): from honey+ moon. The original reference was to affection waning like the moon, but later the sense became 'the first month after marriage'