Just letting you know that in these audio tracks when the first word is the definite article it cannot be heard (for instance here I could not hear the word το before μήκος at all and this has already happened to me twice so I don't know whether it is a problem with every track or a bug)
Yes, check them out.
Most -ος words are masculine but some are neuter or even feminine
-ος words for dimensions are neuter: height = το ύψος, length = το μήκος, breadth, width = το πλάτος (also geogr breadth), το φάρδος, το εύρος (also amplitude)
Nominatve plural (= ackusative pl) is funny: τα ύψη, τα μήκη, τα πλάτη ...