Ich bin unsicher, ob ich das richtige Wort sage.

to be

Breakdown of Ich bin unsicher, ob ich das richtige Wort sage.

• ich: I
• ob: whether
• sagen: to say

Questions & Answers about Ich bin unsicher, ob ich das richtige Wort sage.

What exactly does unsicher mean here, and how is it different from nicht sicher?

Unsicher literally means “uncertain” or “unsure.”

• Ich bin unsicher, ob … = “I am unsure whether…”
• Ich bin nicht sicher, ob … = “I’m not sure whether…”

In this context they mean practically the same thing.

Nuance:

• unsicher is one adjective: you describe your state as “uncertain.”
• nicht sicher negates the adjective sicher (“sure”).

Both are common and natural. If anything, Ich bin mir nicht sicher, ob … is the most idiomatic everyday version (see next question).

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Can I also say Ich bin mir nicht sicher, ob ich das richtige Wort sage? Is that better?

Yes, and many speakers would actually find this version more common and natural in everyday speech:

• Ich bin mir nicht sicher, ob ich das richtige Wort sage.
  Literally: I am myself not sure whether I say the right word.

Differences:

• Ich bin unsicher, ob …
  
  • Slightly more neutral or “descriptive,” could appear in writing or more formal speech, but is fine in conversation too.
• Ich bin mir nicht sicher, ob …
  
  • Extremely common, sounds very idiomatic in spoken German.

Both are correct. If you want the most natural everyday phrasing, use Ich bin mir nicht sicher, ob ….

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