conjunctive adverb
A grammatical term for adverbs that connect clauses or sentences, such as しかし, そして, or したがって.
"However" and "and then" are examples of conjunctive adverbs.
接続詞 (conjunction) is a broader category; 接続副詞 specifically refers to adverbs that function as connectives.
Compound of 接続 (connection) + 副詞 (adverb), a calque from Western grammatical terminology.