| second stomach | segundo estómago |
| Second Sudanese Civil War | Segunda Guerra Civil Sudanesa |
| Second superstring revolution | Segunda revolución de supercuerdas |
| Second Temple | Segundo templo |
| Second Triumvirate | Segundo Triunvirato |
| Second Vatican Council | Concilio Vaticano II |
| Second video of Osama bin Laden surfaces | Segundo video de Osama bin Laden publicado |
| Second Viennese School | Segunda Escuela de Viena |
| Second World | segundo mundo |
| Second World War | Segunda Guerra Mundial |
| second-best | segundo |
| second-class | de segunda clase |
| Second-countable space | Segundo Axioma de Numerabilidad |
| second-degree | de segundo grado |
| second-degree murder | homicidio de segundo grado |
| second-guess | evaluar |
| second-hand | usado |
| second-hand bookshop | libreria de ocasion |
| second-hand buy | ocasión |
| second-hand smoke | fumador pasivo |
| Second-order cybernetics | Cibernética de segundo orden |
| second-person plural | segunda persona del plural |
| second-person singular | segunda persona del singular |
| second-rate | mediocre |
| secondarily | secundariamente |
| secondary | insignificante |
| secondary channel | canal secundario |
| secondary education | educación secundaria |
| Secondary education in France | Liceos en Francia |
| Secondary metabolite | Metabolito secundario |
| Secondary mirror | Espejo secundario |
| secondary school | escuela superior |
| Secondary sector of economic activity | Sector secundario |
| Secondary sector of industry | Sector secundario |
| secondhand | usado |
| secondhand buy | ocasión |
| secondly | en segundo término |
| secondment | comisión de servicio |
| seconds | sobras |
| Seconds From Disaster | Segundos catastróficos |
| secrecy | secreto |
| secret | secreto |
| secret agent | agente secreto |
| secret code | clave |
| secret documents | documentos secretos |
| secret funds | dinero negro |
| Secret Garden | Secret Garden |
| Secret Gospel of Mark | Evangelio secreto de Marcos |
| secret information | información secreta |
| secret of the heart | secreto del corazón |
| Secret of the Runes | Secrets of the runes |
| Secret passage | Pasaje secreto |
| secret police | policía secreta |
