Meaning and name origin
Alasdair \a-las-dair, al(a)-sdair\ as a boy's name (also used as girl's name Alasdair), is pronounced AL-as-dare. It is of Greek origin, and the meaning of Alasdair is "man's defender". Scottish Gaelic form of Alexander, often anglicized as Alistair.
For more information, see also the related boy name Alastair.
Alasdair is not a popular first name for males and an equally uncommon surname or last name for all people (2000 U.S. Census).
Alasdair is also pronounced similarly to Alaisdair, Alisdair, Allysdair and Alysdair. Other suggested similar baby names are Alaistair, Alasteir and Alystair. Like Alasdair, these names are not commonly used.