[jack]

1. Mockingbird: any of a number songbirds which imitate other bird’s calls.
I don't get the underlined part and how come 'songbirds' is not 'songbird'? Also, is 'which' referring to the string 'any of a number songbirds' or just 'songbirds'?

What do these mean?
2. This bird imitates other bird’s call.
4. This bird imitates other birds call.

5. Anisotrophic: having different physical properties at different levels of measurement.
6. Anisotrophic: having different physical properties at different levels of measurements.

7. Dictionary meanings. (Does this mean the word 'dictionary' has many meanings?
8. Dictionary meaning. ('Dictionary' has one meaning?)

9. Tautology: needles repetition of (a) same idea in different wods. (How come I don't need to use a determiner here? If I use it, what does it mean? What's the point of using it and not using it?)