1. to feel happy because you are with someone, or have something.

(What is a suitable English word for the definition?)

2. I am not interested in music at all.
3. I don't take interest in music at all.

(Are both the same and grammatical?)

4. I don't spend a lot of money in buying things.

5. I don't spend a lot of money on buying things.

(Do we have to use 'in' or 'on'?)

# 1... delighted, I was delighted to receive that gift. I was delighted to meet her.

#2 and 3 are both correct.

#4 and 5... neither 'in' not 'on' is needed.

Content???

1. The suitable English word for the definition is "to enjoy" or "to experience joy."

2. Both sentences are grammatical and convey the same meaning. They both indicate a lack of interest in music.

4. Both "in" and "on" can be used in this context, but they slightly alter the meaning of the sentence.
- "I don't spend a lot of money in buying things" implies that you don't spend a large amount of money while you are in the process of purchasing items.
- "I don't spend a lot of money on buying things" suggests that you don't allocate a large budget towards the act of purchasing items.

Overall, both versions are grammatically correct, so the choice depends on the specific emphasis or intention you want to convey.