此外【cǐwài】

此外 adds another point to what has just been said: "in addition", "besides", "apart from this". 此 points back at the previous statement, so 此外 is literally "outside this". It opens its clause or sentence, and 还 or 也 often follows in the same clause. It is neutral to written.

With a negative: nothing else

Followed by 没有 or 不, 此外 means "apart from this, nothing": the earlier statement was the whole list.

此外 or 另外

另外 is the everyday word and does more. It can stand before a noun, meaning "another, other": 另外一个问题 "another question". 此外 only links clauses; it can't describe a noun.

• × 此外一个问题 → 另外一个问题

除了…以外 already means "apart from"; putting 此外 in the same sentence says it twice.

• × 除了上课，此外她还在咖啡馆打工 → 除了上课，她还在咖啡馆打工