女士 (nǚ shì) is the safest, most general polite term for any woman, equivalent to 'Ms.' or 'lady' in English. Unlike 小姐 (xiǎo jiě), which can be offensive in certain contexts, and unlike 太太 (tài tai) or 夫人 (fū rén), which specifically refer to married women, 女士 is appropriate for all adult women in formal or polite address. Its counterpart for men is 男士 (nán shì).