Prefix used in formal or written contexts to refer to the present instance of a period, event, or thing. Common in compounds like 今世紀 (this century), 今シーズン (this season), 今国会 (the current Diet session).
today's
Prefix used in formal or written contexts to refer to today's instance of something. Common in compounds like 今朝 (this morning) and 今夕 (this evening), though those are often read with kun'yomi. The こん reading appears in more formal or technical compounds like 今暁 (this dawn) or 今般 (this time/recently).
It is said to be the greatest discovery of this century.
Our goal for this season is to win the championship.
I would like to report on the recent decision.
The temperature dropped below freezing this dawn.
今日 is the independent everyday word for 'today', while 今 (こん) as a prefix appears only inside formal compounds referring to today's instance of something, like 今暁 or 今般.
The kanji 今 means 'now' or 'present'. The reading こん is the on'yomi (Sino-Japanese reading), used in many compounds to indicate the current or present instance of something.
these days; nowadays; recently
tonight; this evening
this term; this period; current session
this fiscal year; this school year; this year
ancient and modern times; all ages; past and present
this summer; next summer; last summer
this century
this autumn; this fall
this spring; spring this year
this winter; next winter; last winter
past and present; ancient and modern
this life; this world
now; nowadays; the present time
the present day; the present age; nowadays
now; recently; this time
this season
this world; this life · this generation; present day
present-day people; people of this world
this work; this title · modern work not based on old styles
this issue; this number
one's present self