open funnel report – A funnel exploration report that lets users enter the funnel at any step.
opt-in email – Email that is explicitly requested by the recipient.
opt-out – (1) A type of email marketing program that assumes inclusion unless stated otherwise. (2) to remove oneself from an opt-out email marketing program.
organic search – The unpaid entries in a search engine results page that were derived based on their contents’ relevance to the keyword query.
outbound link – A link to a site outside of your site.
owned media – Content created on properties you own or control.