dual

Everyday

1. Having two parts, uses or sides; double. tree →
2. dual nationality / dual citizenship: being a citizen of two countries at the same time. tree →
3. (maths) In some topics, dual means a matching partner shape or idea (for example, a cube and an octahedron are duals). tree →

In the lessons

In everyday life: dual carriageway (a road with two lanes each way, UK), dual-language books, dual controls in a learner car; in maths and geography; phrases: «dual carriageway», «dual citizenship», «dual purpose».

Examples

• My cousin has dual citizenship: Irish and Australian. tree →
• This book is dual-language, English on one page and French on the other. tree →
• Driving schools use cars with dual controls. tree →
• The road becomes a dual carriageway after the roundabout. tree →
• This tool has a dual purpose: a torch and a whistle. tree →
• The game has a dual-screen mode. tree →

Note

Homophone trap: dual (two) vs duel (a fight between two people). Tip: «dual» has «a» like «a pair». Not used about people (do not say «dual twins»).

In Jewish tradition

In everyday life: dual carriageway (a road with two lanes each way, UK), dual-language books, dual controls in a learner car; in maths and geography; phrases: «dual carriageway», «dual citizenship», «dual purpose».

Examples

• It is the Consummation of the Truth of indivi- dual spiritual things. (Sefer Yetzirah, Westcott 1893) tree →

Note

Homophone trap: dual (two) vs duel (a fight between two people). Tip: «dual» has «a» like «a pair». Not used about people (do not say «dual twins»).