zeitlebens
throughout life
During one's whole life; from birth until death.
Sie hat zeitlebens in diesem kleinen Dorf gewohnt.
She lived in this small village throughout her life.

throughout one's life
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throughout life
During one's whole life; from birth until death.
Sie hat zeitlebens in diesem kleinen Dorf gewohnt.
She lived in this small village throughout her life.

'Zeitlebens' (throughout one's life) is made up of the words 'Zeit' (time) and 'Leben' (life). It is a shortened form of the old genitive expression '(seiner) Zeit des Lebens', meaning 'during the time of one's life'.
Er blieb seiner Heimat zeitlebens treu.
He remained loyal to his homeland throughout his life.
As an adverb, 'zeitlebens' (throughout one's life) can stand in position 1; then the verb follows in position 2. It can also stand after the conjugated verb in the middle of the sentence.
Zeitlebens hat er hart für seine Familie gearbeitet.
Throughout his life, he worked hard for his family.
This adverb belongs more to written language or an elevated style. It is used less often in normal everyday conversation.
Die Künstlerin hat zeitlebens für ihre Anerkennung gekämpft.
The artist fought for recognition throughout her life.
at times / temporarily
'zeitweise' and 'zeitlebens' differ mainly in the length of time. 'zeitweise' means that something applies only for a limited time or in individual periods. 'zeitlebens' means that something applies throughout one's whole life. The contrast is therefore: only sometimes or temporarily with 'zeitweise', for one's whole life with 'zeitlebens'.

Der Künstler blieb zeitlebens in seiner Heimatstadt.
The artist remained in his hometown throughout his life.
Aylin wohnt zeitweise bei ihren Eltern, bis sie eine neue Wohnung findet.
Aylin is living with her parents temporarily until she finds a new apartment.