transitive verb
Definition 1
Take up, fill (space).
Source: Concise Oxford Dictionary
Context: Based in the Cabinet Office, he [Nick Clegg] now occupies an office freshly vacated by Lord Mandelson. "It's about five or six times bigger than the office he had in opposition," said an aide.
Source: Financial Times 14/05/2010 (George Parker, Political Editor)
Definition 2
Take possession (of country, region, town, strategic position) by military force or settlement.
Source: Concise Oxford Dictionary
Context: In 1982, the then military government [of Argentina] occupied the two main [Falkland] islands, sparking a 10-week armed conflict which claimed 900 lives.
Source: Financial Times 19/05/2010 (Mark Mulligan in Madrid)
Definition 3
Keep engaged, keep busy.
Source: Invertext, from Concise Oxford Dictionary
Context: Running a leading restaurant and pub group occupies most of Tim Clarke's time.
Source: Financial Times 22/03/2007 (Jamie Chisholm)