Grammarians usually differ in the way they classify words such as moreover, however and therefore. While some group them among conjunctions, others say they are more of adverbials. The words, therefore, come under such terms as ilme ladunni forex, transitional adverbs, conjuctive adverbs or adverbial conjunctions.
Do not be bothered by such conflicting terms. Rather, you need to master the correct usage of the elements, not just in terms of the semantic differences, but also in terms of how best to place them in sentences or paragraphs. To start with, moreover and however are both used to extend statements and show relationships between parts of a sentence, paragraph or passage. But they do not mean the same thing.
That is why it is unfortunate that some indiscriminately use them, thus projecting ideas they do not have in mind. We use moreover when we want to add something in support of a preceding statement. On the other hand, however is used when the speaker or writer wants to take a U-turn from something that he or she has already said. This indicates that if you mix them up, there will be confusion. Moreover, he did not meet the man.
He went there early however, he did not meet the man. However, he did not meet the man. Which do you consider to be the correct statement? The second sentence is also faulty because however and any of the linking words cannot be used as conjunction such as and and but. You need to break the statement into two. Moreover, he called the man on the phone before he set out. Governor el-Rufai has challenged the President.