謹啓[kinkei] Dear Sir or Madam
啓く[hiraku] to enlighten
啓示[keiji] revelation (i.e. divine revelation)
啓発[keihatsu] enlightenment
啓蒙[keimou] enlightenment

啓蟄[keichitsu] "awakening of insects" solar term (approx. Mar. 6, the day on which hibernating insects are said to come out of the ground)
天啓[tenkei] (divine) revelation
拝啓[haikei] Dear (so and so)
啓上[keijou] speaking respectfully
啓迪[keiteki] edification

謹んで[tsutsushinde] respectfully
謹賀新年[kingashinnen] Happy New Year!
謹啓[kinkei] Dear Sir or Madam
謹言[kingen] Yours Sincerely ...
謹慎[kinshin] penitence

謹製[kinsei] quality product
謹聴[kinchou] listening attentively
謹呈[kintei] humbly presenting
重謹慎[juukinshin] close confinement (in one's barracks)
謹み[tsutsushimi] modesty