From close + -ly.

• IPA: /ˈkləʊsliː/

closely (comparative closelier, superlative closeliest)

1. In a close manner.

   Finnish and Estonian are closely related languages.

   The borderline between East and West Berlin was very closely guarded.

   The chairs are too closely spaced; could you move them apart?

2. (obsolete) secretly; privately
   • 1590, Edmund Spenser, “Book III, Canto II”, in The Faerie Queene. […], London: […] [John Wolfe] for William Ponsonbie, →OCLC ↗, stanza 28:

     That nought she did but wayle, and often steepe / Her dainty couch with tears which closely she did weepe.

• French: étroitement
• German: dicht, eng, nah, nahe
• Italian: strettamente, da vicino, a stretto contatto
• Portuguese: de perto, proximamente
• Russian: те́сно
• Spanish: cercanamente