Words are handled differently by different search tools. Many search tools such as Google & Summon assume AND -- so if you enter nursing ethics, you'll retrieve items that contain both words in any order, and perhaps separated by other words.
Do you want a phrase? Use "quotation marks" to indicate a phrase.
For example, in Summon:
Caution: Each interface works differently. Check in the Help to learn how that interface works. For example, phrase searching is NOT recommended in PubMed as it turns off the automatic mapping to MeSH.