A suffix meaning 'a little over' or 'a little more than' when attached after a number (e.g., 2 hours or slightly more).
会議は二時間強で終わった。
The meeting ended in a little over two hours.
荷物の重さは50kg強だった。
The luggage weighed a little over 50 kg.
列車の遅れは30分強で収まった。
The train delay was a little over 30 minutes.
A noun meaning 'the strong' or 'strength'—used in contrastive expressions like 'the strong and the weak'.
演奏では、強と弱のメリハリが大切だ。
In performance, contrasts between loud and soft (strong and weak) are important.
物語では強と弱の関係が描かれている。
The story depicts the relationship between the strong and the weak.
交渉では、強が弱を押し切る場面もある。
In negotiations there are times when the strong prevail over the weak.
A suffix forming words meaning 'powerhouse' or 'one of the most powerful' (e.g., 経済強国 = economic powerhouse).
第二次世界大戦後、日本は経済強国と呼ばれた時期がある。
After World War II, Japan had a period when it was called an economic powerhouse.
その国は軍事強国として知られている。
That country is known as a military powerhouse.
A suffix used in the Japan Meteorological Agency seismic intensity scale to indicate the upper half of an integer level (e.g., 5-strong = 5+).
昨日の地震は震度5強を観測した。
Yesterday's earthquake registered a seismic intensity of 5-strong.
気象庁は震度6強の揺れに注意を呼びかけた。
The Meteorological Agency warned about shaking at seismic intensity 6-strong.