• (GA) enPR: sĕkʹəndlē, IPA: /ˈsɛk.(ə)ndli/, /ˈsɛk.(ə)ntli/
• (RP) IPA: /ˈsɛkəndli/

secondly (not comparable)

1. In the second place.
   • 1992, Rudolf M[athias] Schuster, The Hepaticae and Anthocerotae of North America: East of the Hundredth Meridian, volume V, New York, N.Y.: Columbia University Press, →ISBN, page vii:

     Firstly, I continue to base most species treatments on personally collected material, rather than on herbarium plants. […] Secondly, I continue to base my concepts on intensive study of a limited suite of collections, rather than superficial study of every packet that comes to hand.

• 2ndly
• (less jarring for many speakers) second

• French: deuxièmement
• German: zweitens
• Portuguese: segundamente
• Russian: во-вторы́х