adverb
Used before numbers, quantities, times, distances, and similar expressions to show an approximate amount.
会場には約三百人が集まった。
About three hundred people gathered at the venue.
駅まで歩いて約十分です。
It is about a ten-minute walk to the station.
noun
promise; appointment; engagement
A short Sino-Japanese noun for a promise or engagement; uncommon as a free-standing modern word, where 約束 or 予約 is usually more natural. It appears more readily in set or formal-looking expressions.
「約を違える」は、「約束を破る」という意味のやや硬い表現だ。
約を違える is a somewhat stiff expression meaning 'to break a promise.'
noun
shortening; reduction; simplification
Used mainly as a Sino-Japanese bound element or technical-looking noun for making something shorter, smaller, or simpler, as in compounds related to summarizing or reducing.
「要約」の約には、文章を短くまとめるという意味がある。
The 約 in 要約 carries the sense of shortening and summarizing a text.
数学の「約分」では、分数をより簡単な形にする。
In mathematical 約分, a fraction is reduced to a simpler form.
noun
phonetic contraction
Specialized linguistic use referring to contraction of sounds; closely related to the term 約音.
See also: 約音
言語学の説明で「約音」という語が、音の縮約を指して使われることがある。
In linguistic explanations, the term 約音 may be used to refer to contraction of sounds.
A more explicit word for contraction or reduction, including technical uses; 約 alone is shorter and often bound inside compounds.
Sino-Japanese reading やく of 約. The kanji is conventionally associated with ideas such as binding, agreement, and compression or reduction; the exact historical derivation is not specified.