Explanation for 感 in 感叹词 While beginning to learn Chinese, I encounter 叹词 (tàncí) and 感叹词 (gǎntàncí) for the equivalent meaning of interjection in English. I would like to know why the symbol 感 (gǎn) meaning 'to feel' is added and if there is a resulting difference in meaning. In other words, is it proper grammar or necessary to include the 感 symbol?
There is virtually no difference. Perhaps 嘆詞 is more concise than 感嘆詞.
However, 嘆/叹 itself is seldom used alone in modern Chinese. Modern Chinese tends to use bisyllabic words. So we say 感嘆 (to interject), 讚嘆 (to praise), 嘆息 (to sigh) to 'augment' or 'specify' the meaning of 嘆/叹.
嘆詞 is already bisyllabic; but it still doesn't hurt to say it as 感嘆詞.
感 bears the concept of 'to feel'. You interject after you experienced an emotion. It confers neutrality and generality to the word 感嘆 (compare with 讚嘆, which is fairly positive).