Of or pertaining to us; belonging to us; as, our country; our rights; our troops; our endeavors. See I. [1913 Webster]
" When the noun is not expressed, ours is used in the same way as hers for her, yours for your, etc.; as, whose house is that? It is ours." [1913 Webster]
"The Lord is our defense." [1913 Webster]
"Our wills are ours, we know not how." [1913 Webster]

our, poss.pron. (attrib.)
1 of or belonging to us or ourselves (our house; our own business).
2 of or belonging to all people (our children's future).
3 (esp. as Our) of Us the king or queen, emperor or empress, etc. (given under Our seal).
4 of us, the editorial staff of a newspaper etc. (a foolish adventure in our view).
5 Brit. colloq. indicating a relative, acquaintance, or colleague of the speaker (our Barry works there).

Idiom:
Our Father 1 the Lord's Prayer.
2 God. Our Lady the Virgin Mary.
Our Lord
1 Jesus Christ.
2 God. Our Saviour Jesus Christ.

Etymology:
OE ure orig. genit. pl. of 1st pers. pron. = of us, later treated as possessive adj.

epiphany of our lord, order of our lady of mount carmel, our lady's bedstraw, our lady's mild thistle, our lord's candle, up to our necks