Note that pisteou is a verb.
The larger body of knowledge on this word comes form Ancient Greek Scholars. Their one word translation is "Obey"
Thayer KJV Bible Dictionary
G4100
πιστεύω
pisteuō
Thayer Definition:
1) to think to be true, to be persuaded of, to credit, place confidence in
1a) of the thing believed
1a1) to credit, have confidence
1b) in a moral or religious reference
1b1) used in the NT of the conviction and trust to which a man is impelled by a certain inner and higher prerogative and law of soul
1b2) to trust in Jesus or God as able to aid either in obtaining or in doing something: saving faith
2) to entrust a thing to one, i.e. his fidelity
2a) to be intrusted with a thing
Here's an excerpt on Ancient Greek Verbs:
Ancient Greek verbs have four
moods (
indicative,
imperative,
subjunctive and
optative), three
voices (
active,
middle and
passive), as well as three
persons (first, second and third) and three
numbers (singular, dual and plural).
- In the indicative mood there are seven tenses: present, imperfect, future , aorist (the equivalent of past simple), perfect, pluperfect, and future perfect. (The last two, especially the future perfect, are rarely used).
- In the subjunctive and imperative mood, however, there are only three tenses (present, aorist, and perfect).
- The optative mood, infinitives and participles are found in four tenses (present, aorist, perfect, and future) and all three voices.
The distinction of the "tenses" in moods other than the indicative is predominantly one of
aspect rather than time.
HUH?
Well, that is to say; it needs more than a casual look while my burrito heats up in the microwave 
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