Refers to a place or channel where goods can be sold; a commercial outlet or market.
We are looking for an outlet for this product.
Colloquial use for a chance or opening, especially for employment, marriage, or other life opportunities.
We will develop a new market overseas.
Let me know if there's a good job prospect.
He seems to be looking for a marriage opportunity.
Compound of 売れ (ure, continuative form of 売れる 'to sell') + 口 (kuchi 'mouth; opening'), literally 'selling opening'. The colloquial sense extends the idea of an opening to opportunities in life.