Alasdair sits next to 4 phonetic neighbors — Alistair, Alastair, and Alexander are the closest matches by sound. Most share Alasdair's Scottish cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"defender of men"
"hedgerow, boundary"
"from the court"
"my light, my flame"
"possessor of good"
"father, head of monastery"
"little Hugh"
"mighty hound, great wolf"
"estate by the cliff"
"slender, narrow"
"little drop of water"
"slender, narrow"
"champion, noble one"
"high place, island"
"Ireland, land of the west"
"hospitable"
Similar sound: These names share phonetic patterns with Alasdair — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Greek via Scottish Gaelic origins, giving them the same cultural heritage as Alasdair.
Rhythm: Alasdair is a 3-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.