Serendipity/Serendipitous –  means a “fortunate happenstance” or “pleasant surprise”. .

“What a serendipitous occurrence.”

Coming across something by happy accident – what a fabulous thing to have a word for! Serendipity was coined by Horace Walpole in 1754, from a Persian fairy tale called The Three Princes of Serendip, who were always making lucky discoveries.

My one complaint is that I spent years wanting to spell it ‘serendipidous’ (to go with ‘tremendous’ and other –dous words). But this is a minor quibble only. Accidental good luck – a great thing.