天日|てんぴtenpi[1]atamadaka (head-high)

1. nounthe sun; sunlight; heat of the sun
   果実かじつは天日てんぴで乾燥かんそうさせます。↗

   The fruits are dried in the sun.

• Synonym日光にっこうNeutralNeutral everyday word for sunlight, centered on the sun shining; more ordinary than 「天日」 and not tied to drying.
• Synonym陽光ようこうWrittenWritten word for bright, literary sunshine; 「陽光で干す」 is possible, but drying usually takes 「天日」.
• Synonym日射にっしゃWrittenWritten term for solar radiation, stressing the intensity of the sun's rays, as in 「日射病」; meteorological and medical flavor.
• SynonymサンシャインCasualColloquial loanword for sunshine, seen mostly in names and carrying a bright, cheerful feel.
• Synonym日差しひざしNeutralNeutral everyday word for sunlight or the sun's rays, often with the focus on how strong it feels, as in 「日差しが強い」.
• Synonym太陽光線たいようこうせんWrittenWritten term for the rays of the sun, stressing their physical properties; leans scientific.
• Synonym太陽光たいようこうNeutralNeutral word for sunlight as an energy source, as in 「太陽光発電」; leans technical.
• Antonym日陰ひかげNeutralNeutral word for shade, a spot the sun cannot reach; only in older usage did it mean sunlight, so it differs from 「天日」.
• Antonym夜陰やいんWrittenWritten word for the darkness of night, standing opposite the daytime sunlight of 「天日」.

Use 「天日」 for the sun's light and heat, especially sunlight for drying, as in 「天日干し」 and 「天日塩」. In everyday speech say 「日光」 or 「日差し」; for solar energy say 「太陽光」. The rest are situational: 「陽光」 literary, 「日射」 and 「太陽光線」 technical, 「サンシャイン」 in names, 「日陰」 shade, 「夜陰」 night.

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

1. （てんぴ）太陽たいようの光ひかり。また、その熱ねつ。