IPA: /ˌɪntrəˈθiːkli/
KK: /ɪntrəˈθiːkli/
In a manner that involves the spinal canal, typically referring to the administration of medication directly into the spinal fluid.
The doctor administered the medication intrathecally to ensure it reached the patient's nervous system quickly.
Intrathecally → It is formed from "intra-" (meaning within) and "theca" (from Greek "thēkē", meaning case or sheath) and the suffix "-ly" (meaning in a manner). The word "intrathecally" refers to something that is done within a sheath, particularly in a medical context relating to the spinal canal.
Think of 'intra-' meaning 'within' and 'theca' meaning 'sheath' — this helps you remember that 'intrathecally' refers to something occurring within a protective case.
No commonly confused words.