1
general::
1. Also, better part. The larger amount or majority of something, as in I won't be long; the better half of this job is complete, or I have spent the better part of my life in this city. Sir Philip Sidney used the first term in Arcadia (1580): "I . . . shall think the better half of it already achieved." The variant appears in a well-known proverb, DISCRETION IS THE BETTER PART OF VALOR. 2. Also, my better half. One's (my) spouse, as in I'm not sure if we can go; I'll have to check with my better half. Originally this expression meant "a close friend or lover," and by the 16th century it referred to either a wife or lover. Sidney used it in this way, again in Arcadia: ‘‘My dear, my better half (said he), I find I must now leave thee." Today it tends to be used lightly for either husband or wife. [Late 1500s]
American Heritage Idioms
2
general::
Phrase(s): one’s better half
Fig. one’s spouse. (Usually refers to a wife.) • I think we’d like to come for dinner, but I’ll have to ask my better half. • I have to go home now to my better half. We are going out tonight.
McGrawhill's American Idioms And Phrasal Verbs