past(GRAMMAR)
This is the first person singular preterit ending for verbs belonging to the first conjugation.
One can speculate that some time in the future -mos may become a preterit marker.
For regular verbs the - mos forms are ambiguous between the present and the preterit tenses.

SMART Vocabulary: related words and phrases

Linguistics: verb forms, tenses & types of verbs
accusative
art
auxiliary
bare infinitive
bent
continuous
copula
finite
gerund
modality
non-finite
non-progressive
passive
passivization
perfective
phrasal verb
subjunctive
the active voice
the past continuous
the past tense

Examples of preterit

preterit
Others (they are called weak) add a dental suffix (d or t) in the preterit and the past participle, for example, beg/begged/begged, look/looked/looked, wait/waited/waited.
From Huffington Post
This level contains most of the present tense forms as well as certain preterit forms.
The verb is in the preterit, a perfective past tense, which guarantees that the sentence is episodic.
That would involve the emergence of the preterit, for example, appearing equally in all categories; the same for present, imperfect, and progressive as they emerge.
They were first asked to complete a task to see whether they recognized the morphological distinction between preterit and imperfect.
Since preterit desinences are stressed more frequently than present desinences, this induces a biased surface distribution, with -mosoccurring more frequently with past tense reference.
For regular verbs the -mosforms are ambiguous between the present and the preterit tenses.
The evidential status of the past perfective forms (preterit) is not clear in the narratives in this study although its uses correspond to foreground events.
Sentences with a verb in the preterit (or the perfect) existentially quantify over a single event, hence the episodic interpretation.
In other words, the high rate of marking of preterits in comparison to non-preterits is illusory.
The overall distribution, then, shows preterit forms mainly on the higher levels of the hierarchy, whereas the present is found mostly on the lower levels.
For the younger speakers, however, even a salient form has less chance of occurring with -mosif it is not a preterit.
Level 3 contains only present tense forms, whereas level 4 has preterit as well as a few present tense forms.
In particular, preterit forms can occur only on levels 2, 4, and 5 and are concentrated mainly in levels 4 and 5.
The first two, however, are preterit, and the last is present.
These examples are from corpora and from sources on the web. Any opinions in the examples do not represent the opinion of the Cambridge Dictionary editors or of Cambridge University Press or its licensors.