other
alone, by oneself
A1
'alleine' is a variant of 'allein' meaning 'alone' or 'by oneself'. Used as adjective or adverb. Spelling 'alleine' is common in speech and informal writing; 'allein' is the traditional form and often preferred in formal contexts. No reflexive usage required; meanings identical in most contexts.
Examples
Als Maria alleine blieb, arbeitete sie konzentrierter, weil niemand sie störte.
When Maria stayed alone, she worked more focused because nobody disturbed her.
Ich wohne alleine in der kleinen Wohnung.
I live alone in the small apartment.
Er hat die Aufgabe alleine gemacht.
He did the task by himself.
Details
Mnemonics
imagine a single person standing alone on an island
sounds like English 'alone'
Notes
Used both attributively and adverbially; 'allein' and 'alleine' are often interchangeable in modern German.