1.
lightness; light weight; lack of heaviness
The physical quality of being light in weight, or the degree to which something is not heavy.
このカバンは軽さが魅力だ。
The appeal of this bag is its lightness.
素材の軽さと丈夫さを両立させた製品だ。
This is a product that achieves both lightness and durability of material.
登山では荷物の軽さが体力の消耗に大きく影響するので、持ち物は厳選した方がいい。
When mountain climbing, the lightness of your gear greatly affects how much energy you use, so it's better to be selective about what you bring.
2.
lightness of manner; casualness; frivolity
A quality of being easygoing, casual, or lacking seriousness. Can be positive (approachability) or negative (superficiality).
彼の発言の軽さが問題になった。
The frivolity of his remarks became a problem.
あの人の軽さが好きだ。
I like that person's easygoing manner.
彼女の軽さのある話し方のおかげで、初対面の人でもすぐに打ち解けることができる。
Thanks to her light, casual way of speaking, even people meeting her for the first time can relax and open up quickly.
Formed from the i-adjective 軽い by replacing い with さ, following the standard pattern for turning i-adjectives into nouns expressing degree or quality.
Sense 1 (physical lightness) is straightforward and always positive. Sense 2 (lightness of manner) is ambiguous — it can be a compliment describing approachability and ease, or a criticism implying lack of seriousness or depth.
COMMON COLLOCATIONS:
- 軽さが魅力: lightness is the appeal
- 驚くほどの軽さ: surprising lightness
- 発言の軽さ: frivolity of one's words
- 身の軽さ: physical agility; nimbleness
SIMILAR WORDS:
- 重さ: heaviness; weight — the antonym, formed the same way from 重い
- 軽量: lightweight — a more technical, compound word used for products and materials
- 気軽さ: casualness; ease — specifically about attitude or atmosphere, always positive