Use 'dept' as an abbreviation in informal writing or to save space, like in emails or signs. Please report to the HR dept for your orientation.
Pro Tip 2/3
Context Recognition
Remember that 'dept' implies a specific area within a larger entity, specialized in certain functions. She's studying in the university's languages dept.
Pro Tip 3/3
Spoken Language
In spoken English, always pronounce it fully as 'department' to avoid confusion. I need to visit the finance department, not 'finance dept.'