Último vs. pasado vs. anterior
In Spanish, the terms 'último', 'pasado', and 'anterior' can all translate to 'last' in English. However, each word has a specific contextual meaning in Spanish, which differentiates them from each other.
Último
'Último' typically refers to the most recent event or item in a series or a scenario where periodic repetition is implied. It is usually used when referring to the last in order (the latest).
Él fue el último en llegar a la fiesta.
(He was the last to arrive at the party.)
Esta es la última página del libro.
(This is the last page of the book.)
La última vez que lo vi fue en diciembre.
(The last time I saw him was in December.)
Pasado
'Pasado' often refers to the last complete unit of time and it is commonly used with periods of time, such as week, month or year.
No te vi el mes pasado.
(I did not see you last month.)
Él visitó España el año pasado.
(He visited Spain last year.)
El pasado lunes asistí a una conferencia.
(Last Monday I attended a conference.)
Anterior
'Anterior' is used to refer to the one before in an ordered sequence, including both time and space.
Ella vivía en la casa anterior.
(She lived in the previous house.)
La semana anterior estuvimos de vacaciones.
(We were on vacation the previous week.)
El capítulo anterior fue emocionante.
(The previous chapter was exciting.)
Summary
While 'último', 'pasado', and 'anterior' can all be translated as 'last', they are used differently. 'Último' denotes the most recent event or item. 'Pasado' is often associated with units of time denoting recently passed time intervals like weeks, months or years; and 'anterior' refers to the prior item in an ordered sequence regardless of time.