How to say "meridian" in Japanese

• 子午線しごせんCommon
  nounThe common word for the geographic sense: a meridian on the Earth's surface, i.e. a line of longitude. For 'meridian' in maps, globes and geography, this is the default choice.
  日本にっぽんの子午線しごせんは東経とうけい１３５度どです。↗

  Japan is on the 135th meridian East.
• 経絡けいらく
  nounOnly the traditional Chinese medicine sense: the meridians of the body, familiar from acupuncture. It never refers to geographic lines, so it is wrong for the geography sense of 'meridian'.
• 経線けいせん
  no-adjectiveAlso the geographic sense: a meridian line on a globe or map, running north–south; it can also mean longitude. A less common alternative to 子午線 for the same idea.
• メリディアン
  nounA katakana transliteration of 'meridian'. It is seldom the word you want in ordinary Japanese text; for actual usage, choose 子午線 for geography or 経絡 for the traditional-medicine sense.

Use 子午線 or 経線 for the geographic meridian lines of longitude, 経絡 only for the body's meridians in traditional Chinese medicine, and 「メリディアン」 essentially only when the English loanword itself is wanted.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• 子午線しごせんmeridian
• 経絡けいらくmeridian (in traditional Chinese medicine)
• 経線けいせんmeridian
• メリディアンmeridian