From Old English 'long' and PIE *dlonghos — English inherited the word twice: natively and through Latin 'longitude.'
Measuring a great distance from end to end; lasting or taking a great amount of time.
From Old English 'long' or 'lang,' from Proto-Germanic *langaz, from PIE *dlongʰos meaning 'long.' The PIE root is also the source of Latin 'longus' (long), from which English borrowed 'longitude,' 'elongate,' and 'oblong.' The remarkable thing about 'long' is that the native Germanic word and the Latin borrowings
English inherited the PIE root *dlongʰos twice: once through Germanic as 'long,' and again through Latin 'longus' in borrowed words like 'longitude,' 'elongate,' and 'oblong.' The initial 'dl-' cluster was simplified differently in each branch — Germanic dropped the 'd,' while Latin dropped it separately.