From French réaliser. Surface etymology is real + -ise.
realise (third-person singular simple present realises, present participle realising, simple past and past participle realised)
- Non-Oxford British English standard spelling of realize.
2013 June 7, Ed Pilkington, “‘Killer robots’ should be banned in advance, UN told”, in The Guardian Weekly, volume 188, number 26, page 6:
In his submission to the UN, [Christof] Heyns points to the experience of drones. Unmanned aerial vehicles were intended initially only for surveillance, and their use for offensive purposes was prohibited, yet once strategists realised their perceived advantages as a means of carrying out targeted killings, all objections were swept out of the way.
- “realize” in the Canadian Oxford Dictionary, Second Edition, Oxford University Press, 2004.
- “realize” in Dictionary.com Unabridged, Dictionary.com, LLC, 1995–present.
- “realise” in Douglas Harper, Online Etymology Dictionary, 2001–2019.