主要|しゅようshuyou[0]heiban (flat)

1. na-adjective, nounchief; main; principal; major
   日本にっぽんの主要しゅよう作物さくもつは米こめである。↗

   The main crop of Japan is rice.

• Synonym主だったおもだったNeutralA neutral pre-noun word for the leading ones among many, as in 「主だったメンバー」; it only modifies nouns directly, and 「主要」 is the more common choice.
• Synonym中心的ちゅうしんてきNeutralRefers to something occupying the central position, as in 「中心的な役割」; the point is being at the center rather than dominating the whole.
• SynonymプライマリNeutralA loanword meaning primary or elementary, used mostly in specialist fields such as 「プライマリケア」.
• Related肝心かんじんNeutralMeans crucial or essential, as in 「肝心なところ」; it stresses being indispensable, while 「主要」 stresses holding the leading position.
• Related肝要かんようWrittenWritten language for being vitally important, as in 「～が肝要だ」; close in sense to 「肝心」 but more literary.
• Related緊要きんようWrittenFormal written language for something both urgent and important, as in 「緊要な課題」; it carries a sense of pressing urgency.
• Related枢要すうようWrittenFormal written language for a pivotal, key position, as in 「枢要な地位」; rarely used in everyday speech.
• Related第一義的だいいちぎてきWrittenMeans the most fundamental and first in priority, as in 「第一義的な目的」; it belongs to written, discursive prose, while 「主要」 stresses dominance.
• Related切要せつようWrittenA rare written word meaning extremely pressing or essential; in daily speech say 「重要」 or 「肝要」 instead.
• Antonym副次WrittenThe antonym: secondary or incidental, as in 「副次的な効果」; it stands opposite the leading status expressed by 「主要」.

Use 「主要」 for something that holds the dominant, leading position. For what is crucial or indispensable choose 「肝心」, or the more literary 「肝要」 in writing; for what sits at the center use 「中心的」. For what is secondary, the opposite is 「副次的」.

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

1. 物事ものごとの中心ちゅうしんとなっていて大切たいせつなこと。また、そのさま。