だけれども

だ

け

れ

ど

も

Meanings

A somewhat formal or written-style conjunction that connects contrasting clauses. In casual speech, だけど or けど are more common.

〈事こと〉だけれども、〈事こと〉although X, Y (contrasting two statements)
彼かれは忙いそがしいだけれども、必かならず時じ間かんを作つくってくれる。
He's busy, but he always makes time for me.

だけどN3
だけれども is more formal or written-style, while だけど is the everyday casual equivalent used in spoken Japanese.
けれどN4
けれども has the same formal register as だけれども but drops the だ copula, so it attaches directly after nouns and na-adjectives.
けどN5
けど is an even more casual and frequent contraction than だけれども, often used mid-sentence in conversation.
しかしN4
しかし is a formal written conjunction placed at the start of a new sentence, whereas だけれども joins two clauses within one sentence.
でもN5
でも is a casual sentence-initial 'but' used in speech, while だけれども is more formal and typically connects clauses mid-sentence.

Formed from the copula だ + けれども (conjunction meaning 'but' or 'although').