deber

Senses

1. 1.

   to have to / must

   obligation or necessity

2. 2.

   to owe

   be indebted for money or a favor

3. 3.

   should / ought to

   moral or logical obligation (conditional sense)

4. 4.

   must / probably

   logical deduction or probability

Examples

• "Debo terminar el trabajo antes de las cinco."

  I have to finish the work before five o'clock.

• "Te debo cien euros desde hace meses."

  I've owed you a hundred euros for months.

• "Deberías descansar un poco; pareces cansado."

  You should rest a bit; you look tired.

Usage

Deber + infinitive expresses obligation or necessity; deber de + infinitive (less common) suggests probability or logical deduction. As a transitive verb with a direct object, deber means "to owe." Watch the subtle distinction between debo (I must/have to) and debería (I should), the latter being softer and more advisory.