昨年

1. Origins, structure, and basic meaning

• Structure: 昨年 is read as さくねん and is a noun and time expression meaning the year immediately before the current one.
• Basic usage: An action in the previous year appears in 昨年植えた, while a season in that year appears in 昨年の秋.

2. Common pitfalls and similar expressions

• The year before the reference year
  • It normally refers to the year directly before the present reference point and can function adverbially in a sentence.
• Difference from 去年
  • The meaning is the same, but this term better suits reports and formal writing, while the comparison term is common in conversation.