もっとも, sometimes also seen as 尤（もっと）も, is a 接続詞（せつぞくし） (conjunction) that is used to clarify when (A) is not the only important thing to be considered. This expression is usually translated as ‘although’. However, ‘for all that’, or ‘with that said’ are also accurate translations, depending on the context. Let’s look at a few examples.

• 私（わたし）の妹（いもうと）はピアノを弾（ひ）くのがじょうずだ。もっとも、弾（ひ）けるのは一曲（いっきょく）だけだ。
  My sister is good at playing the piano. Although, she can only play one song.
• 俺（おれ）はすき焼（や）きが大好（だいす）きだ。もっとも、毎日（まいにち）食（た）べれる訳（わけ）では無（な）い。
  I love sukiyaki. Although, it does not mean that I can eat it everyday.

Due to もっとも offering clarification about something, the (B) phrase will often end with が, けど, けれども, and other similar expressions.
When もっとも is used, the speaker is agreeing that (A) is true, but not the whole picture. As a noun itself, 尤（もっと）も can be described as 道理に適（かな）う, which means ‘to stand to reason’. This nuance is kept, and may also be used as an accurate translation for もっとも as a conjunction.

• 私（わたし）は韓国（かんこく）についてものすごく詳（くわ）しいです。もっとも、韓国（かんこく）には行（い）った事（こと）が無（な）いけど。
  I am very knowledgeable about Korea, although I have never been.
• 今日（きょう）は会社（かいしゃ）に自分（じぶん）のパソコンを持（も）ってきた。もっとも、自分（じぶん）のパソコンはいらないが。
  I brought my own computer to work today, although I don't need to.